Repository: letsencrypt/boulder

Issue:
CA and cert-checker need to know whether to allow Test CT logs
The RA [configures its log list](https://github.com/letsencrypt/boulder/blob/01eee61012219862d8db7252fa1c099961f32603/cmd/boulder-ra/main.go#L221) based on a boolean indicating whether it should [submit to test logs](https://github.com/letsencrypt/boulder/blob/01eee61012219862d8db7252fa1c099961f32603/ctpolicy/ctconfig/ctconfig.go#L27-L29). We set that boolean to True in Staging, giving that environment access to CT logs that aren't actually Usable in browsers.

However, the [CA](https://github.com/letsencrypt/boulder/blob/01eee61012219862d8db7252fa1c099961f32603/cmd/boulder-ca/main.go#L162) and the [cert-checker](https://github.com/letsencrypt/boulder/blob/01eee61012219862d8db7252fa1c099961f32603/cmd/cert-checker/main.go#L619) both also use the log list in order to power our [e_scts_from_same_operator custom lint](https://github.com/letsencrypt/boulder/blob/01eee61012219862d8db7252fa1c099961f32603/linter/lints/chrome/e_scts_from_same_operator.go#L33). But when those components build their loglist for that lint, they _unconditionally_ say [no test logs](https://github.com/letsencrypt/boulder/blob/01eee61012219862d8db7252fa1c099961f32603/ctpolicy/loglist/lintlist.go#L25).

Historically we haven't run into this bug because we've been using different log lists in prod and staging, neither of which marked any logs as "Test" logs. Now we're switching to use a single log list in both environments, distinguishing which logs can be used by the log list's built-in "Test" indicator. When we tried to do so, Staging's lints immediately started failing, because none of the test logs used there were included in the lint's log list, and therefore the lint believed that no RFC6962-compliant logs has provided SCTs for the cert.

We can temporarily disable this lint in Staging, but that's not a good long term fix. We need a way for the CA and cert-checker to correctly initialize their lint loglist with or without Test logs, as appropriate.

Hints from issue comments:

Solution patch:
diff --git a/bdns/dns.go b/bdns/dns.go
index 5fee207b8..ea91a5c43 100644
--- a/bdns/dns.go
+++ b/bdns/dns.go
@@ -8,11 +8,8 @@ import (
 	"io"
 	"net"
 	"net/http"
-	"net/netip"
-	"slices"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/jmhodges/clock"
@@ -20,32 +17,57 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 
-	"github.com/letsencrypt/boulder/iana"
 	blog "github.com/letsencrypt/boulder/log"
 	"github.com/letsencrypt/boulder/metrics"
 )
 
-// ResolverAddrs contains DNS resolver(s) that were chosen to perform a
-// validation request or CAA recheck. A ResolverAddr will be in the form of
-// host:port, A:host:port, or AAAA:host:port depending on which type of lookup
-// was done.
-type ResolverAddrs []string
+// Result is a wrapper around miekg/dns.Msg, but with all Resource Records from
+// the Answer section which match the parameterized record type already pulled
+// out for convenient access.
+type Result[R dns.RR] struct {
+	*dns.Msg
+	CNames []*dns.CNAME
+	Final  []R
+}
+
+// resultFromMsg returns a Result whose CNames and Final fields are populated
+// from the underlying Msg's Answer field.
+func resultFromMsg[R dns.RR](m *dns.Msg) *Result[R] {
+	var cnames []*dns.CNAME
+	var final []R
+	for _, rr := range m.Answer {
+		if a, ok := rr.(R); ok {
+			final = append(final, a)
+		} else if a, ok := rr.(*dns.CNAME); ok {
+			cnames = append(cnames, a)
+		}
+	}
+
+	return &Result[R]{
+		Msg:    m,
+		CNames: cnames,
+		Final:  final,
+	}
+}
 
-// Client queries for DNS records
+// Client can make A, AAAA, CAA, and TXT queries. The second return value of
+// each method is the address of the resolver used to conduct the query, and
+// should be populated even when returning an error.
 type Client interface {
-	LookupTXT(context.Context, string) (txts []string, resolver ResolverAddrs, err error)
-	LookupHost(context.Context, string) ([]netip.Addr, ResolverAddrs, error)
-	LookupCAA(context.Context, string) ([]*dns.CAA, string, ResolverAddrs, error)
+	LookupA(context.Context, string) (*Result[*dns.A], string, error)
+	LookupAAAA(context.Context, string) (*Result[*dns.AAAA], string, error)
+	LookupCAA(context.Context, string) (*Result[*dns.CAA], string, error)
+	LookupTXT(context.Context, string) (*Result[*dns.TXT], string, error)
 }
 
-// impl represents a client that talks to an external resolver
+// impl implements the Client interface via an underlying DNS exchanger. It
+// rotates queries across multiple resolvers and tracks a variety of metrics.
 type impl struct {
-	dnsClient                exchanger
-	servers                  ServerProvider
-	allowRestrictedAddresses bool
-	maxTries                 int
-	clk                      clock.Clock
-	log                      blog.Logger
+	exchanger exchanger
+	servers   ServerProvider
+	maxTries  int
+	clk       clock.Clock
+	log       blog.Logger
 
 	queryTime       *prometheus.HistogramVec
 	totalLookupTime *prometheus.HistogramVec
@@ -54,15 +76,9 @@ type impl struct {
 
 var _ Client = &impl{}
 
-type exchanger interface {
-	Exchange(m *dns.Msg, a string) (*dns.Msg, time.Duration, error)
-}
-
-// New constructs a new DNS resolver object that utilizes the
-// provided list of DNS servers for resolution.
-//
-// `tlsConfig` is the configuration used for outbound DoH queries,
-// if applicable.
+// New constructs a new DNS resolver object that utilizes the provided list of
+// DNS servers for resolution, and the provided tlsConfig to speak DoH to those
+// servers.
 func New(
 	readTimeout time.Duration,
 	servers ServerProvider,
@@ -73,18 +89,15 @@ func New(
 	log blog.Logger,
 	tlsConfig *tls.Config,
 ) Client {
-	var client exchanger
-
-	// Clone the default transport because it comes with various settings
-	// that we like, which are different from the zero value of an
-	// `http.Transport`.
+	// Clone the default transport because it comes with various settings that we
+	// like, which are different from the zero value of an `http.Transport`. Then
+	// set it to force HTTP/2, because Unbound will reject non-HTTP/2 DoH
+	// requests.
 	transport := http.DefaultTransport.(*http.Transport).Clone()
 	transport.TLSClientConfig = tlsConfig
-	// The default transport already sets this field, but it isn't
-	// documented that it will always be set. Set it again to be sure,
-	// because Unbound will reject non-HTTP/2 DoH requests.
 	transport.ForceAttemptHTTP2 = true
-	client = &dohExchanger{
+
+	exchanger := &dohExchanger{
 		clk: clk,
 		hc: http.Client{
 			Timeout:   readTimeout,
@@ -107,100 +120,85 @@ func New(
 			Help:    "Time taken to perform a DNS lookup, including all retried queries",
 			Buckets: metrics.InternetFacingBuckets,
 		},
-		[]string{"qtype", "result", "retries", "resolver"},
+		[]string{"qtype", "result", "resolver", "attempts"},
 	)
 	timeoutCounter := promauto.With(stats).NewCounterVec(
 		prometheus.CounterOpts{
 			Name: "dns_timeout",
 			Help: "Counter of various types of DNS query timeouts",
 		},
-		[]string{"qtype", "type", "resolver", "isTLD"},
+		[]string{"qtype", "result", "resolver", "isTLD"},
 	)
-	return &impl{
-		dnsClient:                client,
-		servers:                  servers,
-		allowRestrictedAddresses: false,
-		maxTries:                 maxTries,
-		clk:                      clk,
-		queryTime:                queryTime,
-		totalLookupTime:          totalLookupTime,
-		timeoutCounter:           timeoutCounter,
-		log:                      log,
+
+	if maxTries < 1 {
+		// Allowing negative or zero total attempts makes no sense, so default to 1.
+		maxTries = 1
 	}
-}
 
-// NewTest constructs a new DNS resolver object that utilizes the
-// provided list of DNS servers for resolution and will allow loopback addresses.
-// This constructor should *only* be called from tests (unit or integration).
-func NewTest(
-	readTimeout time.Duration,
-	servers ServerProvider,
-	stats prometheus.Registerer,
-	clk clock.Clock,
-	maxTries int,
-	userAgent string,
-	log blog.Logger,
-	tlsConfig *tls.Config,
-) Client {
-	resolver := New(readTimeout, servers, stats, clk, maxTries, userAgent, log, tlsConfig)
-	resolver.(*impl).allowRestrictedAddresses = true
-	return resolver
+	return &impl{
+		exchanger:       exchanger,
+		servers:         servers,
+		maxTries:        maxTries,
+		clk:             clk,
+		queryTime:       queryTime,
+		totalLookupTime: totalLookupTime,
+		timeoutCounter:  timeoutCounter,
+		log:             log,
+	}
 }
 
-// exchangeOne performs a single DNS exchange with a randomly chosen server
-// out of the server list, returning the response, time, and error (if any).
-// We assume that the upstream resolver requests and validates DNSSEC records
-// itself.
-func (dnsClient *impl) exchangeOne(ctx context.Context, hostname string, qtype uint16) (resp *dns.Msg, resolver string, err error) {
-	m := new(dns.Msg)
+// exchangeOne performs a single DNS exchange with a randomly chosen server out
+// of the server list, returning the response, resolver used, and error (if
+// any). If a response received indicates that the resolver encountered an error
+// (such as an expired DNSSEC signature), that is converted into an error and
+// returned.
+func (c *impl) exchangeOne(ctx context.Context, hostname string, qtype uint16) (*dns.Msg, string, error) {
+	req := new(dns.Msg)
 	// Set question type
-	m.SetQuestion(dns.Fqdn(hostname), qtype)
+	req.SetQuestion(dns.Fqdn(hostname), qtype)
 	// Set the AD bit in the query header so that the resolver knows that
 	// we are interested in this bit in the response header. If this isn't
 	// set the AD bit in the response is useless (RFC 6840 Section 5.7).
 	// This has no security implications, it simply allows us to gather
 	// metrics about the percentage of responses that are secured with
 	// DNSSEC.
-	m.AuthenticatedData = true
+	req.AuthenticatedData = true
 	// Tell the resolver that we're willing to receive responses up to 4096 bytes.
 	// This happens sometimes when there are a very large number of CAA records
 	// present.
-	m.SetEdns0(4096, false)
+	req.SetEdns0(4096, false)
 
-	servers, err := dnsClient.servers.Addrs()
+	servers, err := c.servers.Addrs()
 	if err != nil {
 		return nil, "", fmt.Errorf("failed to list DNS servers: %w", err)
 	}
-	chosenServerIndex := 0
-	chosenServer := servers[chosenServerIndex]
-	resolver = chosenServer
-
-	// Strip off the IP address part of the server address because
-	// we talk to the same server on multiple ports, and don't want
-	// to blow up the cardinality.
-	chosenServerIP, _, err := net.SplitHostPort(chosenServer)
-	if err != nil {
-		return
-	}
 
-	start := dnsClient.clk.Now()
-	client := dnsClient.dnsClient
+	// Prepare to increment a latency metric no matter whether we succeed or fail.
+	// The deferred function closes over resp, chosenServerIP, and tries, which
+	// are all modified in the loop below.
+	start := c.clk.Now()
 	qtypeStr := dns.TypeToString[qtype]
-	tries := 1
+	var (
+		resp           *dns.Msg
+		chosenServerIP string
+		tries          int
+	)
 	defer func() {
 		result := "failed"
 		if resp != nil {
 			result = dns.RcodeToString[resp.Rcode]
 		}
-		dnsClient.totalLookupTime.With(prometheus.Labels{
+		c.totalLookupTime.With(prometheus.Labels{
 			"qtype":    qtypeStr,
 			"result":   result,
-			"retries":  strconv.Itoa(tries),
 			"resolver": chosenServerIP,
-		}).Observe(dnsClient.clk.Since(start).Seconds())
+			"attempts": strconv.Itoa(tries),
+		}).Observe(c.clk.Since(start).Seconds())
 	}()
-	for {
-		ch := make(chan dnsResp, 1)
+
+	for i := range c.maxTries {
+		tries = i + 1
+		chosenServer := servers[i%len(servers)]
 
 		// Strip off the IP address part of the server address because
 		// we talk to the same server on multiple ports, and don't want
@@ -209,224 +207,96 @@ func (dnsClient *impl) exchangeOne(ctx context.Context, hostname string, qtype u
 		// and ensures that chosenServer can't be a bare port, e.g. ":1337"
 		chosenServerIP, _, err = net.SplitHostPort(chosenServer)
 		if err != nil {
-			return
+			return nil, chosenServer, err
 		}
 
-		go func() {
-			rsp, rtt, err := client.Exchange(m, chosenServer)
-			result := "failed"
-			if rsp != nil {
-				result = dns.RcodeToString[rsp.Rcode]
-			}
-			if err != nil {
-				dnsClient.log.Infof("logDNSError chosenServer=[%s] hostname=[%s] queryType=[%s] err=[%s]",
-					chosenServer,
-					hostname,
-					qtypeStr,
-					err)
-			}
-			dnsClient.queryTime.With(prometheus.Labels{
-				"qtype":    qtypeStr,
-				"result":   result,
-				"resolver": chosenServerIP,
-			}).Observe(rtt.Seconds())
-			ch <- dnsResp{m: rsp, err: err}
-		}()
-		select {
-		case <-ctx.Done():
-			if ctx.Err() == context.DeadlineExceeded {
-				dnsClient.timeoutCounter.With(prometheus.Labels{
+		// Do a bare assignment (not :=) to populate the `resp` used by the defer above.
+		var rtt time.Duration
+		resp, rtt, err = c.exchanger.ExchangeContext(ctx, req, chosenServer)
+
+		// Do some metrics handling before we do error handling.
+		result := "failed"
+		if resp != nil {
+			result = dns.RcodeToString[resp.Rcode]
+		}
+		c.queryTime.With(prometheus.Labels{
+			"qtype":    qtypeStr,
+			"result":   result,
+			"resolver": chosenServerIP,
+		}).Observe(rtt.Seconds())
+
+		if err != nil {
+			c.log.Infof("logDNSError chosenServer=[%s] hostname=[%s] queryType=[%s] err=[%s]", chosenServer, hostname, qtypeStr, err)
+
+			// Check if the error is a network timeout, rather than a local context
+			// timeout. If it is, retry instead of giving up.
+			var netErr net.Error
+			isRetryable := ctx.Err() == nil && errors.As(err, &netErr) && netErr.Timeout()
+			hasRetriesLeft := tries < c.maxTries
+			if isRetryable && hasRetriesLeft {
+				continue
+			} else if isRetryable && !hasRetriesLeft {
+				c.timeoutCounter.With(prometheus.Labels{
 					"qtype":    qtypeStr,
-					"type":     "deadline exceeded",
+					"result":   "out of retries",
 					"resolver": chosenServerIP,
-					"isTLD":    isTLD(hostname),
+					"isTLD":    fmt.Sprintf("%t", !strings.Contains(hostname, ".")),
 				}).Inc()
-			} else if ctx.Err() == context.Canceled {
-				dnsClient.timeoutCounter.With(prometheus.Labels{
+			} else if errors.Is(err, context.DeadlineExceeded) {
+				c.timeoutCounter.With(prometheus.Labels{
 					"qtype":    qtypeStr,
-					"type":     "canceled",
+					"result":   "deadline exceeded",
 					"resolver": chosenServerIP,
-					"isTLD":    isTLD(hostname),
+					"isTLD":    fmt.Sprintf("%t", !strings.Contains(hostname, ".")),
 				}).Inc()
-			} else {
-				dnsClient.timeoutCounter.With(prometheus.Labels{
+			} else if errors.Is(err, context.Canceled) {
+				c.timeoutCounter.With(prometheus.Labels{
 					"qtype":    qtypeStr,
-					"type":     "unknown",
+					"result":   "canceled",
 					"resolver": chosenServerIP,
+					"isTLD":    fmt.Sprintf("%t", !strings.Contains(hostname, ".")),
 				}).Inc()
 			}
-			err = ctx.Err()
-			return
-		case r := <-ch:
-			if r.err != nil {
-				var isRetryable bool
-				// Check if the error is a timeout error. Network errors
-				// that can timeout implement the net.Error interface.
-				var netErr net.Error
-				isRetryable = errors.As(r.err, &netErr) && netErr.Timeout()
-				hasRetriesLeft := tries < dnsClient.maxTries
-				if isRetryable && hasRetriesLeft {
-					tries++
-					// Chose a new server to retry the query with by incrementing the
-					// chosen server index modulo the number of servers. This ensures that
-					// if one dns server isn't available we retry with the next in the
-					// list.
-					chosenServerIndex = (chosenServerIndex + 1) % len(servers)
-					chosenServer = servers[chosenServerIndex]
-					resolver = chosenServer
-					continue
-				} else if isRetryable && !hasRetriesLeft {
-					dnsClient.timeoutCounter.With(prometheus.Labels{
-						"qtype":    qtypeStr,
-						"type":     "out of retries",
-						"resolver": chosenServerIP,
-						"isTLD":    isTLD(hostname),
-					}).Inc()
-				}
-			}
-			resp, err = r.m, r.err
-			return
+
+			return nil, chosenServer, err
 		}
-	}
-}
 
-// isTLD returns a simplified view of whether something is a TLD: does it have
-// any dots in it? This returns true or false as a string, and is meant solely
-// for Prometheus metrics.
-func isTLD(hostname string) string {
-	if strings.Contains(hostname, ".") {
-		return "false"
-	} else {
-		return "true"
+		return resp, chosenServer, nil
 	}
-}
 
-type dnsResp struct {
-	m   *dns.Msg
-	err error
+	// It's impossible to get past the bottom of the loop: on the last attempt
+	// (when tries == c.maxTries), all paths lead to a return from inside the loop.
+	return nil, "", errors.New("unexpected loop escape in exchangeOne")
 }
 
-// LookupTXT sends a DNS query to find all TXT records associated with
-// the provided hostname which it returns along with the returned
-// DNS authority section.
-func (dnsClient *impl) LookupTXT(ctx context.Context, hostname string) ([]string, ResolverAddrs, error) {
-	var txt []string
-	dnsType := dns.TypeTXT
-	r, resolver, err := dnsClient.exchangeOne(ctx, hostname, dnsType)
-	errWrap := wrapErr(dnsType, hostname, r, err)
-	if errWrap != nil {
-		return nil, ResolverAddrs{resolver}, errWrap
-	}
-
-	for _, answer := range r.Answer {
-		if answer.Header().Rrtype == dnsType {
-			if txtRec, ok := answer.(*dns.TXT); ok {
-				txt = append(txt, strings.Join(txtRec.Txt, ""))
-			}
-		}
+// LookupA sends a DNS query to find all A records associated with the provided
+// hostname.
+func (c *impl) LookupA(ctx context.Context, hostname string) (*Result[*dns.A], string, error) {
+	resp, resolver, err := c.exchangeOne(ctx, hostname, dns.TypeA)
+	err = wrapErr(dns.TypeA, hostname, resp, err)
+	if err != nil {
+		return nil, resolver, err
 	}
 
-	return txt, ResolverAddrs{resolver}, err
-}
-
-func (dnsClient *impl) lookupIP(ctx context.Context, hostname string, ipType uint16) ([]dns.RR, string, error) {
-	resp, resolver, err := dnsClient.exchangeOne(ctx, hostname, ipType)
-	switch ipType {
-	case dns.TypeA:
-		if resolver != "" {
-			resolver = "A:" + resolver
-		}
-	case dns.TypeAAAA:
-		if resolver != "" {
-			resolver = "AAAA:" + resolver
-		}
-	}
-	errWrap := wrapErr(ipType, hostname, resp, err)
-	if errWrap != nil {
-		return nil, resolver, errWrap
-	}
-	return resp.Answer, resolver, nil
+	return resultFromMsg[*dns.A](resp), resolver, nil
 }
 
-// LookupHost sends a DNS query to find all A and AAAA records associated with
-// the provided hostname. This method assumes that the external resolver will
-// chase CNAME/DNAME aliases and return relevant records. It will retry
-// requests in the case of temporary network errors. It returns an error if
-// both the A and AAAA lookups fail or are empty, but succeeds otherwise.
-func (dnsClient *impl) LookupHost(ctx context.Context, hostname string) ([]netip.Addr, ResolverAddrs, error) {
-	var recordsA, recordsAAAA []dns.RR
-	var errA, errAAAA error
-	var resolverA, resolverAAAA string
-	var wg sync.WaitGroup
-
-	wg.Go(func() {
-		recordsA, resolverA, errA = dnsClient.lookupIP(ctx, hostname, dns.TypeA)
-	})
-	wg.Go(func() {
-		recordsAAAA, resolverAAAA, errAAAA = dnsClient.lookupIP(ctx, hostname, dns.TypeAAAA)
-	})
-	wg.Wait()
-
-	resolvers := ResolverAddrs{resolverA, resolverAAAA}
-	resolvers = slices.DeleteFunc(resolvers, func(a string) bool {
-		return a == ""
-	})
-
-	var addrsA []netip.Addr
-	if errA == nil {
-		for _, answer := range recordsA {
-			if answer.Header().Rrtype == dns.TypeA {
-				a, ok := answer.(*dns.A)
-				if ok && a.A.To4() != nil {
-					netIP, ok := netip.AddrFromSlice(a.A)
-					if ok && (iana.IsReservedAddr(netIP) == nil || dnsClient.allowRestrictedAddresses) {
-						addrsA = append(addrsA, netIP)
-					}
-				}
-			}
-		}
-		if len(addrsA) == 0 {
-			errA = fmt.Errorf("no valid A records found for %s", hostname)
-		}
-	}
-
-	var addrsAAAA []netip.Addr
-	if errAAAA == nil {
-		for _, answer := range recordsAAAA {
-			if answer.Header().Rrtype == dns.TypeAAAA {
-				aaaa, ok := answer.(*dns.AAAA)
-				if ok && aaaa.AAAA.To16() != nil {
-					netIP, ok := netip.AddrFromSlice(aaaa.AAAA)
-					if ok && (iana.IsReservedAddr(netIP) == nil || dnsClient.allowRestrictedAddresses) {
-						addrsAAAA = append(addrsAAAA, netIP)
-					}
-				}
-			}
-		}
-		if len(addrsAAAA) == 0 {
-			errAAAA = fmt.Errorf("no valid AAAA records found for %s", hostname)
-		}
-	}
-
-	if errA != nil && errAAAA != nil {
-		// Construct a new error from both underlying errors. We can only use %w for
-		// one of them, because the go error unwrapping protocol doesn't support
-		// branching. We don't use ProblemDetails and SubProblemDetails here, because
-		// this error will get wrapped in a DNSError and further munged by higher
-		// layers in the stack.
-		return nil, resolvers, fmt.Errorf("%w; %s", errA, errAAAA)
+// LookupAAAA sends a DNS query to find all AAAA records associated with the
+// provided hostname.
+func (c *impl) LookupAAAA(ctx context.Context, hostname string) (*Result[*dns.AAAA], string, error) {
+	resp, resolver, err := c.exchangeOne(ctx, hostname, dns.TypeAAAA)
+	err = wrapErr(dns.TypeAAAA, hostname, resp, err)
+	if err != nil {
+		return nil, resolver, err
 	}
 
-	return append(addrsA, addrsAAAA...), resolvers, nil
+	return resultFromMsg[*dns.AAAA](resp), resolver, nil
 }
 
-// LookupCAA sends a DNS query to find all CAA records associated with
-// the provided hostname and the complete dig-style RR `response`. This
-// response is quite verbose, however it's only populated when the CAA
-// response is non-empty.
-func (dnsClient *impl) LookupCAA(ctx context.Context, hostname string) ([]*dns.CAA, string, ResolverAddrs, error) {
-	dnsType := dns.TypeCAA
-	r, resolver, err := dnsClient.exchangeOne(ctx, hostname, dnsType)
+// LookupCAA sends a DNS query to find all CAA records associated with the
+// provided hostname.
+func (c *impl) LookupCAA(ctx context.Context, hostname string) (*Result[*dns.CAA], string, error) {
+	resp, resolver, err := c.exchangeOne(ctx, hostname, dns.TypeCAA)
 
 	// Special case: when checking CAA for non-TLD names, treat NXDOMAIN as a
 	// successful response containing an empty set of records. This can come up in
@@ -434,36 +304,47 @@ func (dnsClient *impl) LookupCAA(ctx context.Context, hostname string) ([]*dns.C
 	// for DNS-01 challenge) and then removed after validation but before CAA
 	// rechecking. But allow NXDOMAIN for TLDs to fall through to the error code
 	// below, so we don't issue for gTLDs that have been removed by ICANN.
-	if err == nil && r.Rcode == dns.RcodeNameError && strings.Contains(hostname, ".") {
-		return nil, "", ResolverAddrs{resolver}, nil
+	if err == nil && resp.Rcode == dns.RcodeNameError && strings.Contains(hostname, ".") {
+		return resultFromMsg[*dns.CAA](resp), resolver, nil
 	}
 
-	errWrap := wrapErr(dnsType, hostname, r, err)
-	if errWrap != nil {
-		return nil, "", ResolverAddrs{resolver}, errWrap
+	err = wrapErr(dns.TypeCAA, hostname, resp, err)
+	if err != nil {
+		return nil, resolver, err
 	}
 
-	var CAAs []*dns.CAA
-	for _, answer := range r.Answer {
-		if caaR, ok := answer.(*dns.CAA); ok {
-			CAAs = append(CAAs, caaR)
-		}
-	}
-	var response string
-	if len(CAAs) > 0 {
-		response = r.String()
+	return resultFromMsg[*dns.CAA](resp), resolver, nil
+}
+
+// LookupTXT sends a DNS query to find all TXT records associated with the
+// provided hostname.
+func (c *impl) LookupTXT(ctx context.Context, hostname string) (*Result[*dns.TXT], string, error) {
+	resp, resolver, err := c.exchangeOne(ctx, hostname, dns.TypeTXT)
+	err = wrapErr(dns.TypeTXT, hostname, resp, err)
+	if err != nil {
+		return nil, resolver, err
 	}
-	return CAAs, response, ResolverAddrs{resolver}, nil
+
+	return resultFromMsg[*dns.TXT](resp), resolver, nil
+}
+
+// exchanger represents an underlying DNS client. This interface exists solely
+// so that its implementation can be swapped out in unit tests.
+type exchanger interface {
+	ExchangeContext(ctx context.Context, m *dns.Msg, a string) (*dns.Msg, time.Duration, error)
 }
 
+// dohExchanger implements the exchanger interface. It routes all of its DNS
+// queries over DoH, wrapping the request with the appropriate headers and
+// unwrapping the response.
 type dohExchanger struct {
 	clk       clock.Clock
 	hc        http.Client
 	userAgent string
 }
 
-// Exchange sends a DoH query to the provided DoH server and returns the response.
-func (d *dohExchanger) Exchange(query *dns.Msg, server string) (*dns.Msg, time.Duration, error) {
+// ExchangeContext sends a DoH query to the provided DoH server and returns the response.
+func (d *dohExchanger) ExchangeContext(ctx context.Context, query *dns.Msg, server string) (*dns.Msg, time.Duration, error) {
 	q, err := query.Pack()
 	if err != nil {
 		return nil, 0, err
@@ -471,7 +352,7 @@ func (d *dohExchanger) Exchange(query *dns.Msg, server string) (*dns.Msg, time.D
 
 	// The default Unbound URL template
 	url := fmt.Sprintf("https://%s/dns-query", server)
-	req, err := http.NewRequest("POST", url, strings.NewReader(string(q)))
+	req, err := http.NewRequestWithContext(ctx, "POST", url, strings.NewReader(string(q)))
 	if err != nil {
 		return nil, 0, err
 	}
diff --git a/bdns/mocks.go b/bdns/mocks.go
index 5852aac17..d9c3b15ef 100644
--- a/bdns/mocks.go
+++ b/bdns/mocks.go
@@ -3,159 +3,29 @@ package bdns
 import (
 	"context"
 	"errors"
-	"fmt"
-	"net"
-	"net/netip"
-	"os"
 
 	"github.com/miekg/dns"
-
-	blog "github.com/letsencrypt/boulder/log"
 )
 
 // MockClient is a mock
-type MockClient struct {
-	Log blog.Logger
-}
+type MockClient struct{}
 
 // LookupTXT is a mock
-func (mock *MockClient) LookupTXT(_ context.Context, hostname string) ([]string, ResolverAddrs, error) {
-	// Use the example account-specific label prefix derived from
-	// "https://example.com/acme/acct/ExampleAccount"
-	const accountLabelPrefix = "_ujmmovf2vn55tgye._acme-challenge"
-
-	if hostname == accountLabelPrefix+".servfail.com" {
-		// Mirror dns-01 servfail behaviour
-		return nil, ResolverAddrs{"MockClient"}, fmt.Errorf("SERVFAIL")
-	}
-	if hostname == accountLabelPrefix+".good-dns01.com" {
-		// Mirror dns-01 good record
-		// base64(sha256("LoqXcYV8q5ONbJQxbmR7SCTNo3tiAXDfowyjxAjEuX0"
-		//               + "." + "9jg46WB3rR_AHD-EBXdN7cBkH1WOu0tA3M9fm21mqTI"))
-		return []string{"LPsIwTo7o8BoG0-vjCyGQGBWSVIPxI-i_X336eUOQZo"}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == accountLabelPrefix+".wrong-dns01.com" {
-		// Mirror dns-01 wrong record
-		return []string{"a"}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == accountLabelPrefix+".wrong-many-dns01.com" {
-		// Mirror dns-01 wrong-many record
-		return []string{"a", "b", "c", "d", "e"}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == accountLabelPrefix+".long-dns01.com" {
-		// Mirror dns-01 long record
-		return []string{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == accountLabelPrefix+".no-authority-dns01.com" {
-		// Mirror dns-01 no-authority good record
-		// base64(sha256("LoqXcYV8q5ONbJQxbmR7SCTNo3tiAXDfowyjxAjEuX0"
-		//               + "." + "9jg46WB3rR_AHD-EBXdN7cBkH1WOu0tA3M9fm21mqTI"))
-		return []string{"LPsIwTo7o8BoG0-vjCyGQGBWSVIPxI-i_X336eUOQZo"}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == accountLabelPrefix+".empty-txts.com" {
-		// Mirror dns-01 zero TXT records
-		return []string{}, ResolverAddrs{"MockClient"}, nil
-	}
-
-	if hostname == "_acme-challenge.servfail.com" {
-		return nil, ResolverAddrs{"MockClient"}, fmt.Errorf("SERVFAIL")
-	}
-	if hostname == "_acme-challenge.good-dns01.com" {
-		// base64(sha256("LoqXcYV8q5ONbJQxbmR7SCTNo3tiAXDfowyjxAjEuX0"
-		//               + "." + "9jg46WB3rR_AHD-EBXdN7cBkH1WOu0tA3M9fm21mqTI"))
-		// expected token + test account jwk thumbprint
-		return []string{"LPsIwTo7o8BoG0-vjCyGQGBWSVIPxI-i_X336eUOQZo"}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == "_acme-challenge.wrong-dns01.com" {
-		return []string{"a"}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == "_acme-challenge.wrong-many-dns01.com" {
-		return []string{"a", "b", "c", "d", "e"}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == "_acme-challenge.long-dns01.com" {
-		return []string{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == "_acme-challenge.no-authority-dns01.com" {
-		// base64(sha256("LoqXcYV8q5ONbJQxbmR7SCTNo3tiAXDfowyjxAjEuX0"
-		//               + "." + "9jg46WB3rR_AHD-EBXdN7cBkH1WOu0tA3M9fm21mqTI"))
-		// expected token + test account jwk thumbprint
-		return []string{"LPsIwTo7o8BoG0-vjCyGQGBWSVIPxI-i_X336eUOQZo"}, ResolverAddrs{"MockClient"}, nil
-	}
-	// empty-txts.com always returns zero TXT records
-	if hostname == "_acme-challenge.empty-txts.com" {
-		return []string{}, ResolverAddrs{"MockClient"}, nil
-	}
-
-	// Default fallback
-	return []string{"hostname"}, ResolverAddrs{"MockClient"}, nil
+func (mock *MockClient) LookupTXT(_ context.Context, hostname string) (*Result[*dns.TXT], string, error) {
+	return nil, "MockClient", errors.New("unexpected LookupTXT call on test fake")
 }
 
-// makeTimeoutError returns a a net.OpError for which Timeout() returns true.
-func makeTimeoutError() *net.OpError {
-	return &net.OpError{
-		Err: os.NewSyscallError("ugh timeout", timeoutError{}),
-	}
-}
-
-type timeoutError struct{}
-
-func (t timeoutError) Error() string {
-	return "so sloooow"
-}
-func (t timeoutError) Timeout() bool {
-	return true
+// LookupA is a fake
+func (mock *MockClient) LookupA(_ context.Context, hostname string) (*Result[*dns.A], string, error) {
+	return nil, "MockClient", errors.New("unexpected LookupA call on test fake")
 }
 
-// LookupHost is a mock
-func (mock *MockClient) LookupHost(_ context.Context, hostname string) ([]netip.Addr, ResolverAddrs, error) {
-	if hostname == "always.invalid" ||
-		hostname == "invalid.invalid" {
-		return []netip.Addr{}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == "always.timeout" {
-		return []netip.Addr{}, ResolverAddrs{"MockClient"}, &Error{dns.TypeA, "always.timeout", makeTimeoutError(), -1, nil}
-	}
-	if hostname == "always.error" {
-		err := &net.OpError{
-			Op:  "read",
-			Net: "udp",
-			Err: errors.New("some net error"),
-		}
-		m := new(dns.Msg)
-		m.SetQuestion(dns.Fqdn(hostname), dns.TypeA)
-		m.AuthenticatedData = true
-		m.SetEdns0(4096, false)
-		return []netip.Addr{}, ResolverAddrs{"MockClient"}, &Error{dns.TypeA, hostname, err, -1, nil}
-	}
-	if hostname == "id.mismatch" {
-		err := dns.ErrId
-		m := new(dns.Msg)
-		m.SetQuestion(dns.Fqdn(hostname), dns.TypeA)
-		m.AuthenticatedData = true
-		m.SetEdns0(4096, false)
-		r := new(dns.Msg)
-		record := new(dns.A)
-		record.Hdr = dns.RR_Header{Name: dns.Fqdn(hostname), Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 0}
-		record.A = net.ParseIP("127.0.0.1")
-		r.Answer = append(r.Answer, record)
-		return []netip.Addr{}, ResolverAddrs{"MockClient"}, &Error{dns.TypeA, hostname, err, -1, nil}
-	}
-	// dual-homed host with an IPv6 and an IPv4 address
-	if hostname == "ipv4.and.ipv6.localhost" {
-		return []netip.Addr{
-			netip.MustParseAddr("::1"),
-			netip.MustParseAddr("127.0.0.1"),
-		}, ResolverAddrs{"MockClient"}, nil
-	}
-	if hostname == "ipv6.localhost" {
-		return []netip.Addr{
-			netip.MustParseAddr("::1"),
-		}, ResolverAddrs{"MockClient"}, nil
-	}
-	return []netip.Addr{netip.MustParseAddr("127.0.0.1")}, ResolverAddrs{"MockClient"}, nil
+// LookupAAAA is a fake
+func (mock *MockClient) LookupAAAA(_ context.Context, hostname string) (*Result[*dns.AAAA], string, error) {
+	return nil, "MockClient", errors.New("unexpected LookupAAAA call on test fake")
 }
 
-// LookupCAA returns mock records for use in tests.
-func (mock *MockClient) LookupCAA(_ context.Context, domain string) ([]*dns.CAA, string, ResolverAddrs, error) {
-	return nil, "", ResolverAddrs{"MockClient"}, nil
+// LookupCAA is a fake
+func (mock *MockClient) LookupCAA(_ context.Context, domain string) (*Result[*dns.CAA], string, error) {
+	return nil, "MockClient", errors.New("unexpected LookupCAA call on test fake")
 }
diff --git a/cmd/boulder-ca/main.go b/cmd/boulder-ca/main.go
index 8852553b7..15f3df529 100644
--- a/cmd/boulder-ca/main.go
+++ b/cmd/boulder-ca/main.go
@@ -87,6 +87,11 @@ type Config struct {
 		// https://www.gstatic.com/ct/log_list/v3/log_list_schema.json
 		CTLogListFile string
 
+		// CTIncludeTestLogs allows logs marked as "test" to be included in the
+		// CT log list used for linting. This should be enabled in environments
+		// configured to submit SCTs to test logs.
+		CTIncludeTestLogs bool
+
 		// DisableCertService causes the CertificateAuthority gRPC service to not
 		// start, preventing any certificates or precertificates from being issued.
 		DisableCertService bool
@@ -159,7 +164,7 @@ func main() {
 	// Do this before creating the issuers to ensure the log list is loaded before
 	// the linters are initialized.
 	if c.CA.CTLogListFile != "" {
-		err = loglist.InitLintList(c.CA.CTLogListFile)
+		err = loglist.InitLintList(c.CA.CTLogListFile, c.CA.CTIncludeTestLogs)
 		cmd.FailOnError(err, "Failed to load CT Log List")
 	}
 
diff --git a/cmd/boulder-va/main.go b/cmd/boulder-va/main.go
index fecf2ed7f..ab196c2ff 100644
--- a/cmd/boulder-va/main.go
+++ b/cmd/boulder-va/main.go
@@ -100,28 +100,16 @@ func main() {
 	tlsConfig, err := c.VA.TLS.Load(scope)
 	cmd.FailOnError(err, "tlsConfig config")
 
-	var resolver bdns.Client
-	if !c.VA.DNSAllowLoopbackAddresses {
-		resolver = bdns.New(
-			c.VA.DNSTimeout.Duration,
-			servers,
-			scope,
-			clk,
-			c.VA.DNSTries,
-			c.VA.UserAgent,
-			logger,
-			tlsConfig)
-	} else {
-		resolver = bdns.NewTest(
-			c.VA.DNSTimeout.Duration,
-			servers,
-			scope,
-			clk,
-			c.VA.DNSTries,
-			c.VA.UserAgent,
-			logger,
-			tlsConfig)
-	}
+	resolver := bdns.New(
+		c.VA.DNSTimeout.Duration,
+		servers,
+		scope,
+		clk,
+		c.VA.DNSTries,
+		c.VA.UserAgent,
+		logger,
+		tlsConfig)
+
 	var remotes []va.RemoteVA
 	if len(c.VA.RemoteVAs) > 0 {
 		for _, rva := range c.VA.RemoteVAs {
@@ -155,6 +143,7 @@ func main() {
 		"",
 		iana.IsReservedAddr,
 		c.VA.SlowRemoteTimeout.Duration,
+		c.VA.DNSAllowLoopbackAddresses,
 	)
 	cmd.FailOnError(err, "Unable to create VA server")
 
diff --git a/cmd/cert-checker/main.go b/cmd/cert-checker/main.go
index 13833858c..5e8790d20 100644
--- a/cmd/cert-checker/main.go
+++ b/cmd/cert-checker/main.go
@@ -559,6 +559,11 @@ type Config struct {
 		// https://www.gstatic.com/ct/log_list/v3/log_list_schema.json
 		CTLogListFile string
 
+		// CTIncludeTestLogs allows logs marked as "test" to be included in the
+		// CT log list used for linting. This should be enabled in environments
+		// configured to submit SCTs to test logs.
+		CTIncludeTestLogs bool
+
 		Features features.Config
 	}
 	PA     cmd.PAConfig
@@ -616,7 +621,7 @@ func main() {
 	cmd.FailOnError(err, "Failed to load HostnamePolicyFile")
 
 	if config.CertChecker.CTLogListFile != "" {
-		err = loglist.InitLintList(config.CertChecker.CTLogListFile)
+		err = loglist.InitLintList(config.CertChecker.CTLogListFile, config.CertChecker.CTIncludeTestLogs)
 		cmd.FailOnError(err, "Failed to load CT Log List")
 	}
 
diff --git a/cmd/remoteva/main.go b/cmd/remoteva/main.go
index 43b68d621..e398f1b82 100644
--- a/cmd/remoteva/main.go
+++ b/cmd/remoteva/main.go
@@ -106,28 +106,15 @@ func main() {
 		tlsConfig.ClientAuth = tls.VerifyClientCertIfGiven
 	}
 
-	var resolver bdns.Client
-	if !c.RVA.DNSAllowLoopbackAddresses {
-		resolver = bdns.New(
-			c.RVA.DNSTimeout.Duration,
-			servers,
-			scope,
-			clk,
-			c.RVA.DNSTries,
-			c.RVA.UserAgent,
-			logger,
-			tlsConfig)
-	} else {
-		resolver = bdns.NewTest(
-			c.RVA.DNSTimeout.Duration,
-			servers,
-			scope,
-			clk,
-			c.RVA.DNSTries,
-			c.RVA.UserAgent,
-			logger,
-			tlsConfig)
-	}
+	resolver := bdns.New(
+		c.RVA.DNSTimeout.Duration,
+		servers,
+		scope,
+		clk,
+		c.RVA.DNSTries,
+		c.RVA.UserAgent,
+		logger,
+		tlsConfig)
 
 	vai, err := va.NewValidationAuthorityImpl(
 		resolver,
@@ -142,6 +129,7 @@ func main() {
 		c.RVA.RIR,
 		iana.IsReservedAddr,
 		0,
+		c.RVA.DNSAllowLoopbackAddresses,
 	)
 	cmd.FailOnError(err, "Unable to create Remote-VA server")
 
diff --git a/ctpolicy/ctconfig/ctconfig.go b/ctpolicy/ctconfig/ctconfig.go
index cc71478da..03dfe0189 100644
--- a/ctpolicy/ctconfig/ctconfig.go
+++ b/ctpolicy/ctconfig/ctconfig.go
@@ -11,8 +11,9 @@ type CTConfig struct {
 	// from one operator group to accept a certificate before attempting
 	// submission to a log run by a different operator instead.
 	Stagger config.Duration
-	// LogListFile is a path to a JSON log list file. The file must match Chrome's
-	// schema: https://www.gstatic.com/ct/log_list/v3/log_list_schema.json
+	// LogListFile is the path to a JSON file on disk containing the set of all
+	// logs trusted by Chrome. The file must match the v3 log list schema:
+	// https://www.gstatic.com/ct/log_list/v3/log_list_schema.json
 	LogListFile string `validate:"required"`
 	// SCTLogs is a list of CT log names to submit precerts to in order to get SCTs.
 	SCTLogs []string `validate:"min=1,dive,required"`
diff --git a/ctpolicy/loglist/lintlist.go b/ctpolicy/loglist/lintlist.go
index da1c9891a..da361775c 100644
--- a/ctpolicy/loglist/lintlist.go
+++ b/ctpolicy/loglist/lintlist.go
@@ -9,12 +9,13 @@ var lintlist struct {
 }
 
 // InitLintList creates and stores a loglist intended for linting (i.e. with
-// purpose Validation). We have to store this in a global because the zlint
-// framework doesn't (yet) support configuration, so the e_scts_from_same_operator
-// lint cannot load a log list on its own. Instead, we have the CA call this
-// initialization function at startup, and have the lint call the getter below
-// to get access to the cached list.
-func InitLintList(path string) error {
+// purpose Validation). Test logs are included only when submitToTestLogs is
+// true. We have to store this in a global because the zlint framework doesn't
+// (yet) support configuration, so the e_scts_from_same_operator lint cannot
+// load a log list on its own. Instead, we have the CA call this initialization
+// function at startup, and have the lint call the getter below to get access to
+// the cached list.
+func InitLintList(path string, submitToTestLogs bool) error {
 	lintlist.Do(func() {
 		l, err := New(path)
 		if err != nil {
@@ -22,7 +23,7 @@ func InitLintList(path string) error {
 			return
 		}
 
-		l, err = l.forPurpose(Validation, false)
+		l, err = l.forPurpose(Validation, submitToTestLogs)
 		if err != nil {
 			lintlist.err = err
 			return
diff --git a/va/caa.go b/va/caa.go
index 0a9e248d4..8bd2f1860 100644
--- a/va/caa.go
+++ b/va/caa.go
@@ -154,7 +154,7 @@ type caaResult struct {
 	issuewild       []*dns.CAA
 	criticalUnknown bool
 	dig             string
-	resolvers       bdns.ResolverAddrs
+	resolver        string
 	err             error
 }
 
@@ -213,14 +213,18 @@ func (va *ValidationAuthorityImpl) parallelCAALookup(ctx context.Context, name s
 		// Start the concurrent DNS lookup.
 		wg.Add(1)
 		go func(name string, r *caaResult) {
+			defer wg.Done()
 			r.name = name
-			var records []*dns.CAA
-			records, r.dig, r.resolvers, r.err = va.dnsClient.LookupCAA(ctx, name)
-			if len(records) > 0 {
+			var records *bdns.Result[*dns.CAA]
+			records, r.resolver, r.err = va.dnsClient.LookupCAA(ctx, name)
+			if r.err != nil {
+				return
+			}
+			r.dig = records.String()
+			if len(records.Final) > 0 {
 				r.present = true
 			}
-			r.issue, r.issuewild, r.criticalUnknown = filterCAA(records)
-			wg.Done()
+			r.issue, r.issuewild, r.criticalUnknown = filterCAA(records.Final)
 		}(strings.Join(labels[i:], "."), &results[i])
 	}
 
diff --git a/va/dns.go b/va/dns.go
index 81f68296e..c4dc6a2f0 100644
--- a/va/dns.go
+++ b/va/dns.go
@@ -8,31 +8,82 @@ import (
 	"errors"
 	"fmt"
 	"net/netip"
+	"slices"
 	"strings"
+	"sync"
+
+	"github.com/miekg/dns"
 
 	"github.com/letsencrypt/boulder/bdns"
 	"github.com/letsencrypt/boulder/core"
 	berrors "github.com/letsencrypt/boulder/errors"
+	"github.com/letsencrypt/boulder/iana"
 	"github.com/letsencrypt/boulder/identifier"
 )
 
-// getAddr will query for all A/AAAA records associated with hostname and return
-// the preferred address, the first netip.Addr in the addrs slice, and all
-// addresses resolved. This is the same choice made by the Go internal
-// resolution library used by net/http. If there is an error resolving the
-// hostname, or if no usable IP addresses are available then a berrors.DNSError
-// instance is returned with a nil netip.Addr slice.
-func (va ValidationAuthorityImpl) getAddrs(ctx context.Context, hostname string) ([]netip.Addr, bdns.ResolverAddrs, error) {
-	addrs, resolvers, err := va.dnsClient.LookupHost(ctx, hostname)
-	if err != nil {
-		return nil, resolvers, berrors.DNSError("%v", err)
+// getAddr queries for all A/AAAA records associated with hostname, and returns
+// all valid addresses resolved and the addresses of all resolvers used. If
+// there is an error resolving the hostname, or if no usable IP addresses are
+// available then a berrors.DNSError instance is returned with a nil netip.Addr
+// slice.
+func (va ValidationAuthorityImpl) getAddrs(ctx context.Context, hostname string) ([]netip.Addr, []string, error) {
+	// Kick off both the A and AAAA lookups in parallel.
+	var wg sync.WaitGroup
+
+	var resA *bdns.Result[*dns.A]
+	var resolverA string
+	var errA error
+	wg.Go(func() {
+		resA, resolverA, errA = va.dnsClient.LookupA(ctx, hostname)
+	})
+
+	var resAAAA *bdns.Result[*dns.AAAA]
+	var resolverAAAA string
+	var errAAAA error
+	wg.Go(func() {
+		resAAAA, resolverAAAA, errAAAA = va.dnsClient.LookupAAAA(ctx, hostname)
+	})
+
+	wg.Wait()
+
+	// Collect all non-empty resolvers now, so we can return them along with
+	// either a real result or an error.
+	resolvers := []string{resolverA, resolverAAAA}
+	resolvers = slices.DeleteFunc(resolvers, func(a string) bool {
+		return a == ""
+	})
+
+	var addrsA []netip.Addr
+	if errA == nil {
+		for _, rr := range resA.Final {
+			addr := netip.AddrFrom4([4]byte(rr.A.To4()))
+			if addr.IsValid() && (iana.IsReservedAddr(addr) == nil || va.allowRestrictedAddrs) {
+				addrsA = append(addrsA, addr)
+			}
+		}
+		if len(addrsA) == 0 {
+			errA = fmt.Errorf("no valid A records found for %s", hostname)
+		}
 	}
 
-	if len(addrs) == 0 {
-		// This should be unreachable, as no valid IP addresses being found results
-		// in an error being returned from LookupHost.
-		return nil, resolvers, berrors.DNSError("No valid IP addresses found for %s", hostname)
+	var addrsAAAA []netip.Addr
+	if errAAAA == nil {
+		for _, rr := range resAAAA.Final {
+			addr := netip.AddrFrom16([16]byte(rr.AAAA.To16()))
+			if addr.IsValid() && (iana.IsReservedAddr(addr) == nil || va.allowRestrictedAddrs) {
+				addrsAAAA = append(addrsAAAA, addr)
+			}
+		}
+		if len(addrsAAAA) == 0 {
+			errAAAA = fmt.Errorf("no valid AAAA records found for %s", hostname)
+		}
+	}
+
+	if errA != nil && errAAAA != nil {
+		return nil, nil, berrors.DNSError("%s; %s", errA, errAAAA)
 	}
+
+	addrs := append(addrsAAAA, addrsA...)
 	va.log.Debugf("Resolved addresses for %s: %s", hostname, addrs)
 	return addrs, resolvers, nil
 }
@@ -108,7 +159,7 @@ func (va *ValidationAuthorityImpl) validateDNS(ctx context.Context, ident identi
 	challengeSubdomain := fmt.Sprintf("%s.%s", challengePrefix, ident.Value)
 
 	// Look for the required record in the DNS
-	txts, resolvers, err := va.dnsClient.LookupTXT(ctx, challengeSubdomain)
+	txts, resolver, err := va.dnsClient.LookupTXT(ctx, challengeSubdomain)
 	if err != nil {
 		return nil, berrors.DNSError("%s", err)
 	}
@@ -116,24 +167,24 @@ func (va *ValidationAuthorityImpl) validateDNS(ctx context.Context, ident identi
 	// If there weren't any TXT records return a distinct error message to allow
 	// troubleshooters to differentiate between no TXT records and
 	// invalid/incorrect TXT records.
-	if len(txts) == 0 {
+	if len(txts.Final) == 0 {
 		return nil, berrors.UnauthorizedError("No TXT record found at %s", challengeSubdomain)
 	}
 
-	for _, element := range txts {
-		if element == authorizedKeysDigest {
+	for _, rr := range txts.Final {
+		if strings.Join(rr.Txt, "") == authorizedKeysDigest {
 			// Successful challenge validation
-			return []core.ValidationRecord{{Hostname: ident.Value, ResolverAddrs: resolvers}}, nil
+			return []core.ValidationRecord{{Hostname: ident.Value, ResolverAddrs: []string{resolver}}}, nil
 		}
 	}
 
-	invalidRecord := txts[0]
+	invalidRecord := strings.Join(txts.Final[0].Txt, "")
 	if len(invalidRecord) > 100 {
 		invalidRecord = invalidRecord[0:100] + "..."
 	}
 	var andMore string
-	if len(txts) > 1 {
-		andMore = fmt.Sprintf(" (and %d more)", len(txts)-1)
+	if len(txts.Final) > 1 {
+		andMore = fmt.Sprintf(" (and %d more)", len(txts.Final)-1)
 	}
 	return nil, berrors.UnauthorizedError("Incorrect TXT record %q%s found at %s",
 		invalidRecord, andMore, challengeSubdomain)
diff --git a/va/http.go b/va/http.go
index e7b0ec304..dd9f0a998 100644
--- a/va/http.go
+++ b/va/http.go
@@ -15,7 +15,6 @@ import (
 	"time"
 	"unicode"
 
-	"github.com/letsencrypt/boulder/bdns"
 	"github.com/letsencrypt/boulder/core"
 	berrors "github.com/letsencrypt/boulder/errors"
 	"github.com/letsencrypt/boulder/iana"
@@ -178,8 +177,8 @@ type httpValidationTarget struct {
 	next []netip.Addr
 	// the current IP address being used for validation (if any)
 	cur netip.Addr
-	// the DNS resolver(s) that will attempt to fulfill the validation request
-	resolvers bdns.ResolverAddrs
+	// the DNS resolver(s) that were used to look up the host's IP addresses
+	resolvers []string
 }
 
 // nextIP changes the cur IP by removing the first entry from the next slice and
@@ -209,7 +208,7 @@ func (va *ValidationAuthorityImpl) newHTTPValidationTarget(
 	path string,
 	query string) (*httpValidationTarget, error) {
 	var addrs []netip.Addr
-	var resolvers bdns.ResolverAddrs
+	var resolvers []string
 	switch ident.Type {
 	case identifier.TypeDNS:
 		// Resolve IP addresses for the identifier
diff --git a/va/va.go b/va/va.go
index fd7662622..ccaa28558 100644
--- a/va/va.go
+++ b/va/va.go
@@ -188,22 +188,23 @@ func newDefaultPortConfig() *portConfig {
 type ValidationAuthorityImpl struct {
 	vapb.UnsafeVAServer
 	vapb.UnsafeCAAServer
-	log                blog.Logger
-	dnsClient          bdns.Client
-	issuerDomain       string
-	httpPort           int
-	httpsPort          int
-	tlsPort            int
-	userAgent          string
-	clk                clock.Clock
-	remoteVAs          []RemoteVA
-	maxRemoteFailures  int
-	accountURIPrefixes []string
-	singleDialTimeout  time.Duration
-	slowRemoteTimeout  time.Duration
-	perspective        string
-	rir                string
-	isReservedIPFunc   func(netip.Addr) error
+	log                  blog.Logger
+	dnsClient            bdns.Client
+	issuerDomain         string
+	httpPort             int
+	httpsPort            int
+	tlsPort              int
+	userAgent            string
+	clk                  clock.Clock
+	remoteVAs            []RemoteVA
+	maxRemoteFailures    int
+	accountURIPrefixes   []string
+	singleDialTimeout    time.Duration
+	slowRemoteTimeout    time.Duration
+	perspective          string
+	rir                  string
+	isReservedIPFunc     func(netip.Addr) error
+	allowRestrictedAddrs bool
 
 	metrics *vaMetrics
 }
@@ -225,6 +226,7 @@ func NewValidationAuthorityImpl(
 	rir string,
 	reservedIPChecker func(netip.Addr) error,
 	slowRemoteTimeout time.Duration,
+	allowRestrictedAddrs bool,
 ) (*ValidationAuthorityImpl, error) {
 
 	if len(accountURIPrefixes) == 0 {
@@ -258,10 +260,11 @@ func NewValidationAuthorityImpl(
 		// before timing out. This timeout ignores the base RPC timeout and is strictly
 		// used for the DialContext operations that take place during an
 		// HTTP-01 challenge validation.
-		singleDialTimeout: 10 * time.Second,
-		perspective:       perspective,
-		rir:               rir,
-		isReservedIPFunc:  reservedIPChecker,
+		singleDialTimeout:    10 * time.Second,
+		perspective:          perspective,
+		rir:                  rir,
+		isReservedIPFunc:     reservedIPChecker,
+		allowRestrictedAddrs: allowRestrictedAddrs,
 	}
 
 	return va, nil



Test patch:
diff --git a/bdns/dns_test.go b/bdns/dns_test.go
index f53abb19f..b383c5623 100644
--- a/bdns/dns_test.go
+++ b/bdns/dns_test.go
@@ -10,11 +10,9 @@ import (
 	"log"
 	"net"
 	"net/http"
-	"net/netip"
 	"net/url"
 	"os"
 	"regexp"
-	"slices"
 	"strings"
 	"sync"
 	"testing"
@@ -287,14 +285,20 @@ func TestDNSNoServers(t *testing.T) {
 
 	obj := New(time.Hour, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 1, "", blog.UseMock(), tlsConfig)
 
-	_, resolvers, err := obj.LookupHost(context.Background(), "letsencrypt.org")
-	test.AssertEquals(t, len(resolvers), 0)
+	_, resolver, err := obj.LookupA(context.Background(), "letsencrypt.org")
+	test.AssertEquals(t, resolver, "")
 	test.AssertError(t, err, "No servers")
 
-	_, _, err = obj.LookupTXT(context.Background(), "letsencrypt.org")
+	_, resolver, err = obj.LookupAAAA(context.Background(), "letsencrypt.org")
+	test.AssertEquals(t, resolver, "")
+	test.AssertError(t, err, "No servers")
+
+	_, resolver, err = obj.LookupTXT(context.Background(), "letsencrypt.org")
+	test.AssertEquals(t, resolver, "")
 	test.AssertError(t, err, "No servers")
 
-	_, _, _, err = obj.LookupCAA(context.Background(), "letsencrypt.org")
+	_, resolver, err = obj.LookupCAA(context.Background(), "letsencrypt.org")
+	test.AssertEquals(t, resolver, "")
 	test.AssertError(t, err, "No servers")
 }
 
@@ -304,11 +308,9 @@ func TestDNSOneServer(t *testing.T) {
 
 	obj := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 1, "", blog.UseMock(), tlsConfig)
 
-	_, resolvers, err := obj.LookupHost(context.Background(), "cps.letsencrypt.org")
-	test.AssertEquals(t, len(resolvers), 2)
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
+	_, resolver, err := obj.LookupA(context.Background(), "letsencrypt.org")
 	test.AssertNotError(t, err, "No message")
+	test.AssertEquals(t, resolver, "127.0.0.1:4053")
 }
 
 func TestDNSDuplicateServers(t *testing.T) {
@@ -317,11 +319,9 @@ func TestDNSDuplicateServers(t *testing.T) {
 
 	obj := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 1, "", blog.UseMock(), tlsConfig)
 
-	_, resolvers, err := obj.LookupHost(context.Background(), "cps.letsencrypt.org")
-	test.AssertEquals(t, len(resolvers), 2)
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
+	_, resolver, err := obj.LookupA(context.Background(), "letsencrypt.org")
 	test.AssertNotError(t, err, "No message")
+	test.AssertEquals(t, resolver, "127.0.0.1:4053")
 }
 
 func TestDNSServFail(t *testing.T) {
@@ -331,15 +331,17 @@ func TestDNSServFail(t *testing.T) {
 	obj := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 1, "", blog.UseMock(), tlsConfig)
 	bad := "servfail.com"
 
-	_, _, err = obj.LookupTXT(context.Background(), bad)
+	_, _, err = obj.LookupTXT(context.Background(), "servfail.com")
 	test.AssertError(t, err, "LookupTXT didn't return an error")
 
-	_, _, err = obj.LookupHost(context.Background(), bad)
-	test.AssertError(t, err, "LookupHost didn't return an error")
+	_, _, err = obj.LookupA(context.Background(), bad)
+	test.AssertError(t, err, "LookupA didn't return an error")
 
-	emptyCaa, _, _, err := obj.LookupCAA(context.Background(), bad)
-	test.Assert(t, len(emptyCaa) == 0, "Query returned non-empty list of CAA records")
-	test.AssertError(t, err, "LookupCAA should have returned an error")
+	_, _, err = obj.LookupAAAA(context.Background(), bad)
+	test.AssertError(t, err, "LookupAAAA didn't return an error")
+
+	_, _, err = obj.LookupCAA(context.Background(), bad)
+	test.AssertError(t, err, "LookupCAA didn't return an error")
 }
 
 func TestDNSLookupTXT(t *testing.T) {
@@ -348,113 +350,196 @@ func TestDNSLookupTXT(t *testing.T) {
 
 	obj := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 1, "", blog.UseMock(), tlsConfig)
 
-	a, _, err := obj.LookupTXT(context.Background(), "letsencrypt.org")
-	t.Logf("A: %v", a)
+	_, _, err = obj.LookupTXT(context.Background(), "letsencrypt.org")
 	test.AssertNotError(t, err, "No message")
 
-	a, _, err = obj.LookupTXT(context.Background(), "split-txt.letsencrypt.org")
-	t.Logf("A: %v ", a)
+	txt, _, err := obj.LookupTXT(context.Background(), "split-txt.letsencrypt.org")
 	test.AssertNotError(t, err, "No message")
-	test.AssertEquals(t, len(a), 1)
-	test.AssertEquals(t, a[0], "abc")
+	test.AssertEquals(t, len(txt.Final), 1)
+	test.AssertEquals(t, strings.Join(txt.Final[0].Txt, ""), "abc")
 }
 
-// TODO(#8213): Convert this to a table test.
-func TestDNSLookupHost(t *testing.T) {
+func TestDNSLookupA(t *testing.T) {
 	staticProvider, err := NewStaticProvider([]string{dnsLoopbackAddr})
 	test.AssertNotError(t, err, "Got error creating StaticProvider")
 
 	obj := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 1, "", blog.UseMock(), tlsConfig)
 
-	ip, resolvers, err := obj.LookupHost(context.Background(), "servfail.com")
-	t.Logf("servfail.com - IP: %s, Err: %s", ip, err)
-	test.AssertError(t, err, "Server failure")
-	test.Assert(t, len(ip) == 0, "Should not have IPs")
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
-
-	ip, resolvers, err = obj.LookupHost(context.Background(), "nonexistent.letsencrypt.org")
-	t.Logf("nonexistent.letsencrypt.org - IP: %s, Err: %s", ip, err)
-	test.AssertError(t, err, "No valid A or AAAA records should error")
-	test.Assert(t, len(ip) == 0, "Should not have IPs")
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
-
-	// Single IPv4 address
-	ip, resolvers, err = obj.LookupHost(context.Background(), "cps.letsencrypt.org")
-	t.Logf("cps.letsencrypt.org - IP: %s, Err: %s", ip, err)
-	test.AssertNotError(t, err, "Not an error to exist")
-	test.Assert(t, len(ip) == 1, "Should have IP")
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
-	ip, resolvers, err = obj.LookupHost(context.Background(), "cps.letsencrypt.org")
-	t.Logf("cps.letsencrypt.org - IP: %s, Err: %s", ip, err)
-	test.AssertNotError(t, err, "Not an error to exist")
-	test.Assert(t, len(ip) == 1, "Should have IP")
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
-
-	// Single IPv6 address
-	ip, resolvers, err = obj.LookupHost(context.Background(), "v6.letsencrypt.org")
-	t.Logf("v6.letsencrypt.org - IP: %s, Err: %s", ip, err)
-	test.AssertNotError(t, err, "Not an error to exist")
-	test.Assert(t, len(ip) == 1, "Should not have IPs")
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
-
-	// Both IPv6 and IPv4 address
-	ip, resolvers, err = obj.LookupHost(context.Background(), "dualstack.letsencrypt.org")
-	t.Logf("dualstack.letsencrypt.org - IP: %s, Err: %s", ip, err)
-	test.AssertNotError(t, err, "Not an error to exist")
-	test.Assert(t, len(ip) == 2, "Should have 2 IPs")
-	expected := netip.MustParseAddr("64.112.117.1")
-	test.Assert(t, ip[0] == expected, "wrong ipv4 address")
-	expected = netip.MustParseAddr("2602:80a:6000:abad:cafe::1")
-	test.Assert(t, ip[1] == expected, "wrong ipv6 address")
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
-
-	// IPv6 error, IPv4 success
-	ip, resolvers, err = obj.LookupHost(context.Background(), "v6error.letsencrypt.org")
-	t.Logf("v6error.letsencrypt.org - IP: %s, Err: %s", ip, err)
-	test.AssertNotError(t, err, "Not an error to exist")
-	test.Assert(t, len(ip) == 1, "Should have 1 IP")
-	expected = netip.MustParseAddr("64.112.117.1")
-	test.Assert(t, ip[0] == expected, "wrong ipv4 address")
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
-
-	// IPv6 success, IPv4 error
-	ip, resolvers, err = obj.LookupHost(context.Background(), "v4error.letsencrypt.org")
-	t.Logf("v4error.letsencrypt.org - IP: %s, Err: %s", ip, err)
-	test.AssertNotError(t, err, "Not an error to exist")
-	test.Assert(t, len(ip) == 1, "Should have 1 IP")
-	expected = netip.MustParseAddr("2602:80a:6000:abad:cafe::1")
-	test.Assert(t, ip[0] == expected, "wrong ipv6 address")
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
-
-	// IPv6 error, IPv4 error
-	// Should return both the IPv4 error (Refused) and the IPv6 error (NotImplemented)
-	hostname := "dualstackerror.letsencrypt.org"
-	ip, resolvers, err = obj.LookupHost(context.Background(), hostname)
-	t.Logf("%s - IP: %s, Err: %s", hostname, ip, err)
-	test.AssertError(t, err, "Should be an error")
-	test.AssertContains(t, err.Error(), "REFUSED looking up A for")
-	test.AssertContains(t, err.Error(), "NOTIMP looking up AAAA for")
-	slices.Sort(resolvers)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"A:127.0.0.1:4053", "AAAA:127.0.0.1:4053"})
+	for _, tc := range []struct {
+		name      string
+		hostname  string
+		wantIPs   []net.IP
+		wantError string
+	}{
+		{
+			name:      "SERVFAIL",
+			hostname:  "servfail.com",
+			wantError: "SERVFAIL looking up A for servfail.com",
+		},
+		{
+			name:     "No Records",
+			hostname: "nonexistent.letsencrypt.org",
+			wantIPs:  nil,
+		},
+		{
+			name:     "Single IPv4",
+			hostname: "cps.letsencrypt.org",
+			wantIPs:  []net.IP{net.ParseIP("64.112.117.1")},
+		},
+		{
+			name:     "Single IPv6",
+			hostname: "v6.letsencrypt.org",
+			wantIPs:  nil,
+		},
+		{
+			name:     "Both IPv6 and IPv4",
+			hostname: "dualstack.letsencrypt.org",
+			wantIPs:  []net.IP{net.ParseIP("64.112.117.1")},
+		},
+		{
+			name:     "IPv6 error and IPv4 success",
+			hostname: "v6error.letsencrypt.org",
+			wantIPs:  []net.IP{net.ParseIP("64.112.117.1")},
+		},
+		{
+			name:      "IPv6 success and IPv4 error",
+			hostname:  "v4error.letsencrypt.org",
+			wantError: "NOTIMP looking up A for v4error.letsencrypt.org",
+		},
+		{
+			name:      "Both IPv6 and IPv4 error",
+			hostname:  "dualstackerror.letsencrypt.org",
+			wantError: "REFUSED looking up A for dualstackerror.letsencrypt.org",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			res, resolver, err := obj.LookupA(context.Background(), tc.hostname)
+
+			wantResolver := "127.0.0.1:4053"
+			if resolver != wantResolver {
+				t.Errorf("LookupA(%s) used resolver %q, but want %q", tc.hostname, resolver, wantResolver)
+			}
+
+			if tc.wantError != "" {
+				if err == nil {
+					t.Fatalf("LookupA(%s) = success, but want error %q", tc.hostname, tc.wantError)
+				}
+				if !strings.Contains(err.Error(), tc.wantError) {
+					t.Errorf("LookupA(%s) = %q, but want error %q", tc.hostname, err, tc.wantError)
+				}
+			} else {
+				if err != nil {
+					t.Fatalf("LookupA(%s) = %q, but want success", tc.hostname, err)
+				}
+				if len(res.Final) != len(tc.wantIPs) {
+					t.Fatalf("LookupA(%s) retuned %d addrs, but want %d", tc.hostname, len(res.Final), len(tc.wantIPs))
+				}
+				for i := range len(tc.wantIPs) {
+					if !res.Final[i].A.Equal(tc.wantIPs[i]) {
+						t.Errorf("LookupA(%s) = %s, but want %s", tc.hostname, res.Final[i].A, tc.wantIPs[i])
+					}
+				}
+			}
+		})
+	}
 }
 
-func TestDNSNXDOMAIN(t *testing.T) {
+func TestDNSLookupAAAA(t *testing.T) {
 	staticProvider, err := NewStaticProvider([]string{dnsLoopbackAddr})
 	test.AssertNotError(t, err, "Got error creating StaticProvider")
 
 	obj := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 1, "", blog.UseMock(), tlsConfig)
 
+	for _, tc := range []struct {
+		name      string
+		hostname  string
+		wantIPs   []net.IP
+		wantError string
+	}{
+		{
+			name:      "SERVFAIL",
+			hostname:  "servfail.com",
+			wantError: "SERVFAIL looking up AAAA for servfail.com",
+		},
+		{
+			name:     "No Records",
+			hostname: "nonexistent.letsencrypt.org",
+			wantIPs:  nil,
+		},
+		{
+			name:     "Single IPv4",
+			hostname: "cps.letsencrypt.org",
+			wantIPs:  nil,
+		},
+		{
+			name:     "Single IPv6",
+			hostname: "v6.letsencrypt.org",
+			wantIPs:  []net.IP{net.ParseIP("2602:80a:6000:abad:cafe::1")},
+		},
+		{
+			name:     "Both IPv6 and IPv4",
+			hostname: "dualstack.letsencrypt.org",
+			wantIPs:  []net.IP{net.ParseIP("2602:80a:6000:abad:cafe::1")},
+		},
+		{
+			name:      "IPv6 error and IPv4 success",
+			hostname:  "v6error.letsencrypt.org",
+			wantError: "NOTIMP looking up AAAA for v6error.letsencrypt.org",
+		},
+		{
+			name:     "IPv6 success and IPv4 error",
+			hostname: "v4error.letsencrypt.org",
+			wantIPs:  []net.IP{net.ParseIP("2602:80a:6000:abad:cafe::1")},
+		},
+		{
+			name:      "Both IPv6 and IPv4 error",
+			hostname:  "dualstackerror.letsencrypt.org",
+			wantError: "NOTIMP looking up AAAA for dualstackerror.letsencrypt.org",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			res, resolver, err := obj.LookupAAAA(context.Background(), tc.hostname)
+
+			wantResolver := "127.0.0.1:4053"
+			if resolver != wantResolver {
+				t.Errorf("LookupA(%s) used resolver %q, but want %q", tc.hostname, resolver, wantResolver)
+			}
+
+			if tc.wantError != "" {
+				if err == nil {
+					t.Fatalf("LookupA(%s) = success, but want error %q", tc.hostname, tc.wantError)
+				}
+				if !strings.Contains(err.Error(), tc.wantError) {
+					t.Errorf("LookupA(%s) = %q, but want error %q", tc.hostname, err, tc.wantError)
+				}
+			} else {
+				if err != nil {
+					t.Fatalf("LookupA(%s) = %q, but want success", tc.hostname, err)
+				}
+				if len(res.Final) != len(tc.wantIPs) {
+					t.Fatalf("LookupA(%s) retuned %d addrs, but want %d", tc.hostname, len(res.Final), len(tc.wantIPs))
+				}
+				for i := range len(tc.wantIPs) {
+					if !res.Final[i].AAAA.Equal(tc.wantIPs[i]) {
+						t.Errorf("LookupA(%s) = %s, but want %s", tc.hostname, res.Final[i].AAAA, tc.wantIPs[i])
+					}
+				}
+			}
+		})
+	}
+}
+
+func TestDNSNXDOMAIN(t *testing.T) {
+	staticProvider, err := NewStaticProvider([]string{dnsLoopbackAddr})
+	test.AssertNotError(t, err, "Got error creating StaticProvider")
+
+	obj := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 1, "", blog.UseMock(), tlsConfig)
 	hostname := "nxdomain.letsencrypt.org"
-	_, _, err = obj.LookupHost(context.Background(), hostname)
+
+	_, _, err = obj.LookupA(context.Background(), hostname)
 	test.AssertContains(t, err.Error(), "NXDOMAIN looking up A for")
+
+	_, _, err = obj.LookupAAAA(context.Background(), hostname)
 	test.AssertContains(t, err.Error(), "NXDOMAIN looking up AAAA for")
 
 	_, _, err = obj.LookupTXT(context.Background(), hostname)
@@ -469,11 +554,10 @@ func TestDNSLookupCAA(t *testing.T) {
 	obj := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 1, "", blog.UseMock(), tlsConfig)
 	removeIDExp := regexp.MustCompile(" id: [[:digit:]]+")
 
-	caas, resp, resolvers, err := obj.LookupCAA(context.Background(), "bracewel.net")
+	caas, resolver, err := obj.LookupCAA(context.Background(), "bracewel.net")
 	test.AssertNotError(t, err, "CAA lookup failed")
-	test.Assert(t, len(caas) > 0, "Should have CAA records")
-	test.AssertEquals(t, len(resolvers), 1)
-	test.AssertDeepEquals(t, resolvers, ResolverAddrs{"127.0.0.1:4053"})
+	test.Assert(t, len(caas.Final) > 0, "Should have CAA records")
+	test.AssertEquals(t, resolver, "127.0.0.1:4053")
 	expectedResp := `;; opcode: QUERY, status: NOERROR, id: XXXX
 ;; flags: qr rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
 
@@ -483,27 +567,22 @@ func TestDNSLookupCAA(t *testing.T) {
 ;; ANSWER SECTION:
 bracewel.net.	0	IN	CAA	1 issue "letsencrypt.org"
 `
-	test.AssertEquals(t, removeIDExp.ReplaceAllString(resp, " id: XXXX"), expectedResp)
+	test.AssertEquals(t, removeIDExp.ReplaceAllString(caas.String(), " id: XXXX"), expectedResp)
 
-	caas, resp, resolvers, err = obj.LookupCAA(context.Background(), "nonexistent.letsencrypt.org")
+	caas, resolver, err = obj.LookupCAA(context.Background(), "nonexistent.letsencrypt.org")
 	test.AssertNotError(t, err, "CAA lookup failed")
-	test.Assert(t, len(caas) == 0, "Shouldn't have CAA records")
-	test.AssertEquals(t, resolvers[0], "127.0.0.1:4053")
-	expectedResp = ""
-	test.AssertEquals(t, resp, expectedResp)
+	test.Assert(t, len(caas.Final) == 0, "Shouldn't have CAA records")
+	test.AssertEquals(t, resolver, "127.0.0.1:4053")
 
-	caas, resp, resolvers, err = obj.LookupCAA(context.Background(), "nxdomain.letsencrypt.org")
-	slices.Sort(resolvers)
+	caas, resolver, err = obj.LookupCAA(context.Background(), "nxdomain.letsencrypt.org")
 	test.AssertNotError(t, err, "CAA lookup failed")
-	test.Assert(t, len(caas) == 0, "Shouldn't have CAA records")
-	test.AssertEquals(t, resolvers[0], "127.0.0.1:4053")
-	expectedResp = ""
-	test.AssertEquals(t, resp, expectedResp)
+	test.Assert(t, len(caas.Final) == 0, "Shouldn't have CAA records")
+	test.AssertEquals(t, resolver, "127.0.0.1:4053")
 
-	caas, resp, resolvers, err = obj.LookupCAA(context.Background(), "cname.example.com")
+	caas, resolver, err = obj.LookupCAA(context.Background(), "cname.example.com")
 	test.AssertNotError(t, err, "CAA lookup failed")
-	test.Assert(t, len(caas) > 0, "Should follow CNAME to find CAA")
-	test.AssertEquals(t, resolvers[0], "127.0.0.1:4053")
+	test.Assert(t, len(caas.Final) > 0, "Should follow CNAME to find CAA")
+	test.AssertEquals(t, resolver, "127.0.0.1:4053")
 	expectedResp = `;; opcode: QUERY, status: NOERROR, id: XXXX
 ;; flags: qr rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
 
@@ -513,12 +592,12 @@ bracewel.net.	0	IN	CAA	1 issue "letsencrypt.org"
 ;; ANSWER SECTION:
 caa.example.com.	0	IN	CAA	1 issue "letsencrypt.org"
 `
-	test.AssertEquals(t, removeIDExp.ReplaceAllString(resp, " id: XXXX"), expectedResp)
+	test.AssertEquals(t, removeIDExp.ReplaceAllString(caas.String(), " id: XXXX"), expectedResp)
 
-	_, _, resolvers, err = obj.LookupCAA(context.Background(), "gonetld")
+	_, resolver, err = obj.LookupCAA(context.Background(), "gonetld")
 	test.AssertError(t, err, "should fail for TLD NXDOMAIN")
 	test.AssertContains(t, err.Error(), "NXDOMAIN")
-	test.AssertEquals(t, resolvers[0], "127.0.0.1:4053")
+	test.AssertEquals(t, resolver, "127.0.0.1:4053")
 }
 
 type testExchanger struct {
@@ -529,7 +608,11 @@ type testExchanger struct {
 
 var errTooManyRequests = errors.New("too many requests")
 
-func (te *testExchanger) Exchange(m *dns.Msg, a string) (*dns.Msg, time.Duration, error) {
+func (te *testExchanger) ExchangeContext(ctx context.Context, m *dns.Msg, a string) (*dns.Msg, time.Duration, error) {
+	if ctx.Err() != nil {
+		return nil, 0, ctx.Err()
+	}
+
 	te.Lock()
 	defer te.Unlock()
 	msg := &dns.Msg{
@@ -678,7 +761,7 @@ func TestRetry(t *testing.T) {
 
 			testClient := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), tc.maxTries, "", blog.UseMock(), tlsConfig)
 			dr := testClient.(*impl)
-			dr.dnsClient = tc.te
+			dr.exchanger = tc.te
 			_, _, err = dr.LookupTXT(context.Background(), "example.com")
 			if err == errTooManyRequests {
 				t.Errorf("#%d, sent more requests than the test case handles", i)
@@ -696,68 +779,58 @@ func TestRetry(t *testing.T) {
 				test.AssertMetricWithLabelsEquals(
 					t, dr.timeoutCounter, prometheus.Labels{
 						"qtype":    "TXT",
-						"type":     "out of retries",
+						"result":   "out of retries",
 						"resolver": "127.0.0.1",
 						"isTLD":    "false",
 					}, tc.metricsAllRetries)
 			}
 		})
 	}
+}
 
+func TestRetryMetrics(t *testing.T) {
 	staticProvider, err := NewStaticProvider([]string{dnsLoopbackAddr})
 	test.AssertNotError(t, err, "Got error creating StaticProvider")
 
+	// This lookup should not be retried, because the error comes from the
+	// context itself being cancelled. It should never see the error in the
+	// testExchanger, because the fake exchanger (like the real http package)
+	// checks for cancellation before doing any work.
 	testClient := New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 3, "", blog.UseMock(), tlsConfig)
 	dr := testClient.(*impl)
-	dr.dnsClient = &testExchanger{errs: []error{isTimeoutErr, isTimeoutErr, nil}}
-	ctx, cancel := context.WithCancel(context.Background())
+	dr.exchanger = &testExchanger{errs: []error{errors.New("oops")}}
+	ctx, cancel := context.WithCancel(t.Context())
 	cancel()
 	_, _, err = dr.LookupTXT(ctx, "example.com")
 	if err == nil ||
 		err.Error() != "DNS problem: query timed out (and was canceled) looking up TXT for example.com" {
 		t.Errorf("expected %s, got %s", context.Canceled, err)
 	}
+	test.AssertMetricWithLabelsEquals(
+		t, dr.timeoutCounter, prometheus.Labels{
+			"qtype":    "TXT",
+			"result":   "canceled",
+			"resolver": "127.0.0.1",
+		}, 1)
 
-	dr.dnsClient = &testExchanger{errs: []error{isTimeoutErr, isTimeoutErr, nil}}
-	ctx, cancel = context.WithTimeout(context.Background(), -10*time.Hour)
+	// Same as above, except rather than cancelling the context ourselves, we
+	// let the go runtime cancel it as a result of a deadline in the past.
+	testClient = New(time.Second*10, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 3, "", blog.UseMock(), tlsConfig)
+	dr = testClient.(*impl)
+	dr.exchanger = &testExchanger{errs: []error{errors.New("oops")}}
+	ctx, cancel = context.WithTimeout(t.Context(), -10*time.Hour)
 	defer cancel()
 	_, _, err = dr.LookupTXT(ctx, "example.com")
 	if err == nil ||
 		err.Error() != "DNS problem: query timed out looking up TXT for example.com" {
 		t.Errorf("expected %s, got %s", context.DeadlineExceeded, err)
 	}
-
-	dr.dnsClient = &testExchanger{errs: []error{isTimeoutErr, isTimeoutErr, nil}}
-	ctx, deadlineCancel := context.WithTimeout(context.Background(), -10*time.Hour)
-	deadlineCancel()
-	_, _, err = dr.LookupTXT(ctx, "example.com")
-	if err == nil ||
-		err.Error() != "DNS problem: query timed out looking up TXT for example.com" {
-		t.Errorf("expected %s, got %s", context.DeadlineExceeded, err)
-	}
-
 	test.AssertMetricWithLabelsEquals(
 		t, dr.timeoutCounter, prometheus.Labels{
 			"qtype":    "TXT",
-			"type":     "canceled",
+			"result":   "deadline exceeded",
 			"resolver": "127.0.0.1",
 		}, 1)
-
-	test.AssertMetricWithLabelsEquals(
-		t, dr.timeoutCounter, prometheus.Labels{
-			"qtype":    "TXT",
-			"type":     "deadline exceeded",
-			"resolver": "127.0.0.1",
-		}, 2)
-}
-
-func TestIsTLD(t *testing.T) {
-	if isTLD("com") != "true" {
-		t.Errorf("expected 'com' to be a TLD, got %q", isTLD("com"))
-	}
-	if isTLD("example.com") != "false" {
-		t.Errorf("expected 'example.com' to not a TLD, got %q", isTLD("example.com"))
-	}
 }
 
 type testTimeoutError bool
@@ -775,9 +848,9 @@ type rotateFailureExchanger struct {
 	brokenAddresses map[string]bool
 }
 
-// Exchange for rotateFailureExchanger tracks the `a` argument in `lookups` and
+// ExchangeContext for rotateFailureExchanger tracks the `a` argument in `lookups` and
 // if present in `brokenAddresses`, returns a timeout error.
-func (e *rotateFailureExchanger) Exchange(m *dns.Msg, a string) (*dns.Msg, time.Duration, error) {
+func (e *rotateFailureExchanger) ExchangeContext(_ context.Context, m *dns.Msg, a string) (*dns.Msg, time.Duration, error) {
 	e.Lock()
 	defer e.Unlock()
 
@@ -822,7 +895,7 @@ func TestRotateServerOnErr(t *testing.T) {
 		},
 		lookups: make(map[string]int),
 	}
-	client.(*impl).dnsClient = mock
+	client.(*impl).exchanger = mock
 
 	// Perform a bunch of lookups. We choose the initial server randomly. Any time
 	// A or B is chosen there should be an error and a retry using the next server
@@ -830,9 +903,8 @@ func TestRotateServerOnErr(t *testing.T) {
 	// servers *all* queries should eventually succeed by being retried against
 	// server "[2606:4700:4700::1111]:53".
 	for range maxTries * 2 {
-		_, resolvers, err := client.LookupTXT(context.Background(), "example.com")
-		test.AssertEquals(t, len(resolvers), 1)
-		test.AssertEquals(t, resolvers[0], "[2606:4700:4700::1111]:53")
+		_, resolver, err := client.LookupTXT(context.Background(), "example.com")
+		test.AssertEquals(t, resolver, "[2606:4700:4700::1111]:53")
 		// Any errors are unexpected - server "[2606:4700:4700::1111]:53" should
 		// have responded without error.
 		test.AssertNotError(t, err, "Expected no error from eventual retry with functional server")
@@ -859,7 +931,7 @@ type dohAlwaysRetryExchanger struct {
 	err error
 }
 
-func (dohE *dohAlwaysRetryExchanger) Exchange(m *dns.Msg, a string) (*dns.Msg, time.Duration, error) {
+func (dohE *dohAlwaysRetryExchanger) ExchangeContext(_ context.Context, m *dns.Msg, a string) (*dns.Msg, time.Duration, error) {
 	dohE.Lock()
 	defer dohE.Unlock()
 
@@ -878,7 +950,7 @@ func TestDOHMetric(t *testing.T) {
 
 	testClient := New(time.Second*11, staticProvider, metrics.NoopRegisterer, clock.NewFake(), 0, "", blog.UseMock(), tlsConfig)
 	resolver := testClient.(*impl)
-	resolver.dnsClient = &dohAlwaysRetryExchanger{err: &url.Error{Op: "read", Err: testTimeoutError(true)}}
+	resolver.exchanger = &dohAlwaysRetryExchanger{err: &url.Error{Op: "read", Err: testTimeoutError(true)}}
 
 	// Starting out, we should count 0 "out of retries" errors.
 	test.AssertMetricWithLabelsEquals(t, resolver.timeoutCounter, prometheus.Labels{"qtype": "None", "type": "out of retries", "resolver": "127.0.0.1", "isTLD": "false"}, 0)
diff --git a/bdns/problem_test.go b/bdns/problem_test.go
index 8e925d80b..bdf7040b0 100644
--- a/bdns/problem_test.go
+++ b/bdns/problem_test.go
@@ -7,8 +7,9 @@ import (
 	"net/url"
 	"testing"
 
-	"github.com/letsencrypt/boulder/test"
 	"github.com/miekg/dns"
+
+	"github.com/letsencrypt/boulder/test"
 )
 
 func TestError(t *testing.T) {
@@ -17,9 +18,6 @@ func TestError(t *testing.T) {
 		expected string
 	}{
 		{
-			&Error{dns.TypeA, "hostname", makeTimeoutError(), -1, nil},
-			"DNS problem: query timed out looking up A for hostname",
-		}, {
 			&Error{dns.TypeMX, "hostname", &net.OpError{Err: errors.New("some net error")}, -1, nil},
 			"DNS problem: networking error looking up MX for hostname",
 		}, {
diff --git a/cmd/cert-checker/main_test.go b/cmd/cert-checker/main_test.go
index ed75ec35c..6d3504f72 100644
--- a/cmd/cert-checker/main_test.go
+++ b/cmd/cert-checker/main_test.go
@@ -583,7 +583,7 @@ func TestIgnoredLint(t *testing.T) {
 		saCleanup()
 	}()
 
-	err = loglist.InitLintList("../../test/ct-test-srv/log_list.json")
+	err = loglist.InitLintList("../../test/ct-test-srv/log_list.json", false)
 	test.AssertNotError(t, err, "failed to load ct log list")
 	testKey, _ := rsa.GenerateKey(rand.Reader, 2048)
 	checker := newChecker(saDbMap, clock.NewFake(), pa, kp, time.Hour, testValidityDurations, nil, blog.NewMock())
diff --git a/issuance/cert_test.go b/issuance/cert_test.go
index 67e3675ed..873a5b72c 100644
--- a/issuance/cert_test.go
+++ b/issuance/cert_test.go
@@ -656,7 +656,7 @@ func TestIssueSCTList(t *testing.T) {
 	fc := clock.NewFake()
 	fc.Set(time.Now())
 
-	err := loglist.InitLintList("../test/ct-test-srv/log_list.json")
+	err := loglist.InitLintList("../test/ct-test-srv/log_list.json", false)
 	test.AssertNotError(t, err, "failed to load log list")
 
 	pc := defaultProfileConfig()
@@ -807,7 +807,7 @@ func TestInvalidProfile(t *testing.T) {
 	fc := clock.NewFake()
 	fc.Set(time.Now())
 
-	err := loglist.InitLintList("../test/ct-test-srv/log_list.json")
+	err := loglist.InitLintList("../test/ct-test-srv/log_list.json", false)
 	test.AssertNotError(t, err, "failed to load log list")
 
 	signer, err := newIssuer(defaultIssuerConfig(), issuerCert, issuerSigner, fc)
@@ -850,7 +850,7 @@ func TestInvalidProfile(t *testing.T) {
 func TestMismatchedProfiles(t *testing.T) {
 	fc := clock.NewFake()
 	fc.Set(time.Now())
-	err := loglist.InitLintList("../test/ct-test-srv/log_list.json")
+	err := loglist.InitLintList("../test/ct-test-srv/log_list.json", false)
 	test.AssertNotError(t, err, "failed to load log list")
 
 	issuer1, err := newIssuer(defaultIssuerConfig(), issuerCert, issuerSigner, fc)
diff --git a/va/caa_test.go b/va/caa_test.go
index 3a83dd155..419c18ddf 100644
--- a/va/caa_test.go
+++ b/va/caa_test.go
@@ -26,24 +26,18 @@ import (
 	vapb "github.com/letsencrypt/boulder/va/proto"
 )
 
-// caaMockDNS implements the `dns.DNSClient` interface with a set of useful test
+// caaFakeDNS implements the `dns.DNSClient` interface with a set of useful test
 // answers for CAA queries.
-type caaMockDNS struct{}
-
-func (mock caaMockDNS) LookupTXT(_ context.Context, hostname string) ([]string, bdns.ResolverAddrs, error) {
-	return nil, bdns.ResolverAddrs{"caaMockDNS"}, nil
-}
-
-func (mock caaMockDNS) LookupHost(_ context.Context, hostname string) ([]netip.Addr, bdns.ResolverAddrs, error) {
-	return []netip.Addr{netip.MustParseAddr("127.0.0.1")}, bdns.ResolverAddrs{"caaMockDNS"}, nil
+type caaFakeDNS struct {
+	bdns.Client
 }
 
-func (mock caaMockDNS) LookupCAA(_ context.Context, domain string) ([]*dns.CAA, string, bdns.ResolverAddrs, error) {
+func (mock *caaFakeDNS) LookupCAA(_ context.Context, domain string) (*bdns.Result[*dns.CAA], string, error) {
 	var results []*dns.CAA
 	var record dns.CAA
 	switch strings.TrimRight(domain, ".") {
 	case "caa-timeout.com":
-		return nil, "", bdns.ResolverAddrs{"caaMockDNS"}, fmt.Errorf("error")
+		return nil, "caaFakeDNS", fmt.Errorf("error")
 	case "reserved.com":
 		record.Tag = "issue"
 		record.Value = "ca.com"
@@ -63,11 +57,10 @@ func (mock caaMockDNS) LookupCAA(_ context.Context, domain string) ([]*dns.CAA,
 		results = append(results, &record)
 	case "com":
 		// com has no CAA records.
-		return nil, "", bdns.ResolverAddrs{"caaMockDNS"}, nil
 	case "gonetld":
-		return nil, "", bdns.ResolverAddrs{"caaMockDNS"}, fmt.Errorf("NXDOMAIN")
+		return nil, "caaFakeDNS", fmt.Errorf("NXDOMAIN")
 	case "servfail.com", "servfail.present.com":
-		return results, "", bdns.ResolverAddrs{"caaMockDNS"}, fmt.Errorf("SERVFAIL")
+		return nil, "caaFakeDNS", fmt.Errorf("SERVFAIL")
 	case "multi-crit-present.com":
 		record.Flag = 1
 		record.Tag = "issue"
@@ -185,15 +178,12 @@ func (mock caaMockDNS) LookupCAA(_ context.Context, domain string) ([]*dns.CAA,
 		record.Value = "letsencrypt.org"
 		results = append(results, &record)
 	}
-	var response string
-	if len(results) > 0 {
-		response = "foo"
-	}
-	return results, response, bdns.ResolverAddrs{"caaMockDNS"}, nil
+
+	return &bdns.Result[*dns.CAA]{Final: results}, "caaFakeDNS", nil
 }
 
 func TestCAATimeout(t *testing.T) {
-	va, _ := setup(nil, "", nil, caaMockDNS{})
+	va, _ := setup(nil, "", nil, &caaFakeDNS{})
 
 	params := &caaParams{
 		accountURIID:     12345,
@@ -416,7 +406,7 @@ func TestCAAChecking(t *testing.T) {
 	method := core.ChallengeTypeHTTP01
 	params := &caaParams{accountURIID: accountURIID, validationMethod: method}
 
-	va, _ := setup(nil, "", nil, caaMockDNS{})
+	va, _ := setup(nil, "", nil, &caaFakeDNS{})
 	va.accountURIPrefixes = []string{"https://letsencrypt.org/acct/reg/"}
 
 	for _, caaTest := range testCases {
@@ -439,7 +429,7 @@ func TestCAAChecking(t *testing.T) {
 }
 
 func TestCAALogging(t *testing.T) {
-	va, _ := setup(nil, "", nil, caaMockDNS{})
+	va, _ := setup(nil, "", nil, &caaFakeDNS{})
 
 	testCases := []struct {
 		Name            string
@@ -452,55 +442,55 @@ func TestCAALogging(t *testing.T) {
 			Domain:          "reserved.com",
 			AccountURIID:    12345,
 			ChallengeType:   core.ChallengeTypeHTTP01,
-			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for reserved.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: false, Found at: \"reserved.com\"] Response=\"foo\"",
+			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for reserved.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: false, Found at: \"reserved.com\"] Response=\"<nil> MsgHdr\"",
 		},
 		{
 			Domain:          "reserved.com",
 			AccountURIID:    12345,
 			ChallengeType:   core.ChallengeTypeDNS01,
-			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for reserved.com, [Present: true, Account ID: 12345, Challenge: dns-01, Valid for issuance: false, Found at: \"reserved.com\"] Response=\"foo\"",
+			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for reserved.com, [Present: true, Account ID: 12345, Challenge: dns-01, Valid for issuance: false, Found at: \"reserved.com\"] Response=\"<nil> MsgHdr\"",
 		},
 		{
 			Domain:          "mixedcase.com",
 			AccountURIID:    12345,
 			ChallengeType:   core.ChallengeTypeHTTP01,
-			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for mixedcase.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: false, Found at: \"mixedcase.com\"] Response=\"foo\"",
+			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for mixedcase.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: false, Found at: \"mixedcase.com\"] Response=\"<nil> MsgHdr\"",
 		},
 		{
 			Domain:          "critical.com",
 			AccountURIID:    12345,
 			ChallengeType:   core.ChallengeTypeHTTP01,
-			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for critical.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: false, Found at: \"critical.com\"] Response=\"foo\"",
+			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for critical.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: false, Found at: \"critical.com\"] Response=\"<nil> MsgHdr\"",
 		},
 		{
 			Domain:          "present.com",
 			AccountURIID:    12345,
 			ChallengeType:   core.ChallengeTypeHTTP01,
-			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for present.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: true, Found at: \"present.com\"] Response=\"foo\"",
+			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for present.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: true, Found at: \"present.com\"] Response=\"<nil> MsgHdr\"",
 		},
 		{
 			Domain:          "not.here.but.still.present.com",
 			AccountURIID:    12345,
 			ChallengeType:   core.ChallengeTypeHTTP01,
-			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for not.here.but.still.present.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: true, Found at: \"present.com\"] Response=\"foo\"",
+			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for not.here.but.still.present.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: true, Found at: \"present.com\"] Response=\"<nil> MsgHdr\"",
 		},
 		{
 			Domain:          "multi-crit-present.com",
 			AccountURIID:    12345,
 			ChallengeType:   core.ChallengeTypeHTTP01,
-			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for multi-crit-present.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: true, Found at: \"multi-crit-present.com\"] Response=\"foo\"",
+			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for multi-crit-present.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: true, Found at: \"multi-crit-present.com\"] Response=\"<nil> MsgHdr\"",
 		},
 		{
 			Domain:          "present-with-parameter.com",
 			AccountURIID:    12345,
 			ChallengeType:   core.ChallengeTypeHTTP01,
-			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for present-with-parameter.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: true, Found at: \"present-with-parameter.com\"] Response=\"foo\"",
+			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for present-with-parameter.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: true, Found at: \"present-with-parameter.com\"] Response=\"<nil> MsgHdr\"",
 		},
 		{
 			Domain:          "satisfiable-wildcard-override.com",
 			AccountURIID:    12345,
 			ChallengeType:   core.ChallengeTypeHTTP01,
-			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for satisfiable-wildcard-override.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: false, Found at: \"satisfiable-wildcard-override.com\"] Response=\"foo\"",
+			ExpectedLogline: "INFO: [AUDIT] Checked CAA records for satisfiable-wildcard-override.com, [Present: true, Account ID: 12345, Challenge: http-01, Valid for issuance: false, Found at: \"satisfiable-wildcard-override.com\"] Response=\"<nil> MsgHdr\"",
 		},
 	}
 
@@ -530,7 +520,7 @@ func TestCAALogging(t *testing.T) {
 // includes the domain name that was being checked in the failure detail.
 func TestDoCAAErrMessage(t *testing.T) {
 	t.Parallel()
-	va, _ := setup(nil, "", nil, caaMockDNS{})
+	va, _ := setup(nil, "", nil, &caaFakeDNS{})
 
 	// Call the operation with a domain we know fails with a generic error from the
 	// caaMockDNS.
@@ -556,7 +546,7 @@ func TestDoCAAErrMessage(t *testing.T) {
 // Binding checks.
 func TestDoCAAParams(t *testing.T) {
 	t.Parallel()
-	va, _ := setup(nil, "", nil, caaMockDNS{})
+	va, _ := setup(nil, "", nil, &caaFakeDNS{})
 
 	// Calling IsCAAValid without a ValidationMethod should fail.
 	_, err := va.DoCAA(ctx, &vapb.IsCAAValidRequest{
@@ -593,35 +583,24 @@ var errCAABrokenDNSClient = errors.New("dnsClient is broken")
 
 // caaBrokenDNS implements the `dns.DNSClient` interface, but always returns
 // errors.
-type caaBrokenDNS struct{}
-
-func (b caaBrokenDNS) LookupTXT(_ context.Context, hostname string) ([]string, bdns.ResolverAddrs, error) {
-	return nil, bdns.ResolverAddrs{"caaBrokenDNS"}, errCAABrokenDNSClient
+type caaBrokenDNS struct {
+	bdns.Client
 }
 
-func (b caaBrokenDNS) LookupHost(_ context.Context, hostname string) ([]netip.Addr, bdns.ResolverAddrs, error) {
-	return nil, bdns.ResolverAddrs{"caaBrokenDNS"}, errCAABrokenDNSClient
-}
-
-func (b caaBrokenDNS) LookupCAA(_ context.Context, domain string) ([]*dns.CAA, string, bdns.ResolverAddrs, error) {
-	return nil, "", bdns.ResolverAddrs{"caaBrokenDNS"}, errCAABrokenDNSClient
+func (b caaBrokenDNS) LookupCAA(_ context.Context, domain string) (*bdns.Result[*dns.CAA], string, error) {
+	return nil, "caaBrokenDNS", errCAABrokenDNSClient
 }
 
 // caaHijackedDNS implements the `dns.DNSClient` interface with a set of useful
 // test answers for CAA queries. It returns alternate CAA records than what
-// caaMockDNS returns simulating either a BGP hijack or DNS records that have
+// caaFakeDNS returns simulating either a BGP hijack or DNS records that have
 // changed while queries were inflight.
-type caaHijackedDNS struct{}
-
-func (h caaHijackedDNS) LookupTXT(_ context.Context, hostname string) ([]string, bdns.ResolverAddrs, error) {
-	return nil, bdns.ResolverAddrs{"caaHijackedDNS"}, nil
+type caaHijackedDNS struct {
+	bdns.Client
 }
 
-func (h caaHijackedDNS) LookupHost(_ context.Context, hostname string) ([]netip.Addr, bdns.ResolverAddrs, error) {
-	return []netip.Addr{netip.MustParseAddr("127.0.0.1")}, bdns.ResolverAddrs{"caaHijackedDNS"}, nil
-}
-func (h caaHijackedDNS) LookupCAA(_ context.Context, domain string) ([]*dns.CAA, string, bdns.ResolverAddrs, error) {
-	// These records are altered from their caaMockDNS counterparts. Use this to
+func (b caaHijackedDNS) LookupCAA(_ context.Context, domain string) (*bdns.Result[*dns.CAA], string, error) {
+	// These records are altered from their caaFakeDNS counterparts. Use this to
 	// tickle remoteValidationFailures.
 	var results []*dns.CAA
 	var record dns.CAA
@@ -631,7 +610,7 @@ func (h caaHijackedDNS) LookupCAA(_ context.Context, domain string) ([]*dns.CAA,
 		record.Value = "other-ca.com"
 		results = append(results, &record)
 	case "present-dns-only.com":
-		return results, "", bdns.ResolverAddrs{"caaHijackedDNS"}, fmt.Errorf("SERVFAIL")
+		return nil, "caaHijackedDNS", fmt.Errorf("SERVFAIL")
 	case "satisfiable-wildcard.com":
 		record.Tag = "issuewild"
 		record.Value = ";"
@@ -641,11 +620,8 @@ func (h caaHijackedDNS) LookupCAA(_ context.Context, domain string) ([]*dns.CAA,
 		secondRecord.Value = ";"
 		results = append(results, &secondRecord)
 	}
-	var response string
-	if len(results) > 0 {
-		response = "foo"
-	}
-	return results, response, bdns.ResolverAddrs{"caaHijackedDNS"}, nil
+
+	return &bdns.Result[*dns.CAA]{Final: results}, "caaHijackedDNS", nil
 }
 
 // parseValidationLogEvent extracts ... from JSON={ ... } in a ValidateChallenge
@@ -691,11 +667,11 @@ func TestMultiCAARechecking(t *testing.T) {
 		{
 			name:           "all VAs functional, no CAA records",
 			ident:          identifier.NewDNS("present-dns-only.com"),
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
-				{ua: remoteUA, rir: arin},
-				{ua: remoteUA, rir: ripe},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: arin, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: ripe, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 			expectedLabels: prometheus.Labels{
 				"operation":      opCAA,
@@ -712,9 +688,9 @@ func TestMultiCAARechecking(t *testing.T) {
 			expectedProbSubstring: "While processing CAA for present-dns-only.com: dnsClient is broken",
 			expectedProbType:      probs.DNSProblem,
 			remoteVAs: []remoteConf{
-				{ua: remoteUA, rir: arin},
-				{ua: remoteUA, rir: ripe},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: arin, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: ripe, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 			expectedLabels: prometheus.Labels{
 				"operation":      opCAA,
@@ -727,7 +703,7 @@ func TestMultiCAARechecking(t *testing.T) {
 		{
 			name:                     "functional localVA, 1 broken RVA, no CAA records",
 			ident:                    identifier.NewDNS("present-dns-only.com"),
-			localDNSClient:           caaMockDNS{},
+			localDNSClient:           &caaFakeDNS{},
 			expectedDiffLogSubstring: `"RemoteSuccesses":2,"RemoteFailures":1`,
 			expectedSummary: &mpicSummary{
 				Passed:       []string{"dc-1-RIPE", "dc-2-APNIC"},
@@ -737,8 +713,8 @@ func TestMultiCAARechecking(t *testing.T) {
 			},
 			remoteVAs: []remoteConf{
 				{ua: brokenUA, rir: arin, dns: caaBrokenDNS{}},
-				{ua: remoteUA, rir: ripe},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: ripe, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 			expectedLabels: prometheus.Labels{
 				"operation":      opCAA,
@@ -760,11 +736,11 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{apnic},
 				QuorumResult: "1/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: brokenUA, rir: arin, dns: caaBrokenDNS{}},
 				{ua: brokenUA, rir: ripe, dns: caaBrokenDNS{}},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 			expectedLabels: prometheus.Labels{
 				"operation":      opCAA,
@@ -786,7 +762,7 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{},
 				QuorumResult: "0/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: brokenUA, rir: arin, dns: caaBrokenDNS{}},
 				{ua: brokenUA, rir: ripe, dns: caaBrokenDNS{}},
@@ -803,11 +779,11 @@ func TestMultiCAARechecking(t *testing.T) {
 		{
 			name:           "all VAs functional, CAA issue type present",
 			ident:          identifier.NewDNS("present.com"),
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
-				{ua: remoteUA, rir: arin},
-				{ua: remoteUA, rir: ripe},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: arin, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: ripe, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 			expectedLabels: prometheus.Labels{
 				"operation":      opCAA,
@@ -827,11 +803,11 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{ripe, apnic},
 				QuorumResult: "2/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: brokenUA, rir: arin, dns: caaBrokenDNS{}},
-				{ua: remoteUA, rir: ripe},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: ripe, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 			expectedLabels: prometheus.Labels{
 				"operation":      opCAA,
@@ -853,11 +829,11 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{apnic},
 				QuorumResult: "1/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: brokenUA, rir: arin, dns: caaBrokenDNS{}},
 				{ua: brokenUA, rir: ripe, dns: caaBrokenDNS{}},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 			expectedLabels: prometheus.Labels{
 				"operation":      opCAA,
@@ -879,7 +855,7 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{},
 				QuorumResult: "0/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: brokenUA, rir: arin, dns: caaBrokenDNS{}},
 				{ua: brokenUA, rir: ripe, dns: caaBrokenDNS{}},
@@ -900,11 +876,11 @@ func TestMultiCAARechecking(t *testing.T) {
 			ident:                 identifier.NewDNS("unsatisfiable.com"),
 			expectedProbSubstring: "CAA record for unsatisfiable.com prevents issuance",
 			expectedProbType:      probs.CAAProblem,
-			localDNSClient:        caaMockDNS{},
+			localDNSClient:        &caaFakeDNS{},
 			remoteVAs: []remoteConf{
-				{ua: remoteUA, rir: arin},
-				{ua: remoteUA, rir: ripe},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: arin, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: ripe, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 		},
 		{
@@ -917,11 +893,11 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{ripe, apnic},
 				QuorumResult: "2/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: hijackedUA, rir: arin, dns: caaHijackedDNS{}},
-				{ua: remoteUA, rir: ripe},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: ripe, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 		},
 		{
@@ -936,11 +912,11 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{apnic},
 				QuorumResult: "1/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: hijackedUA, rir: arin, dns: caaHijackedDNS{}},
 				{ua: hijackedUA, rir: ripe, dns: caaHijackedDNS{}},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 		},
 		{
@@ -955,7 +931,7 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{},
 				QuorumResult: "0/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: hijackedUA, rir: arin, dns: caaHijackedDNS{}},
 				{ua: hijackedUA, rir: ripe, dns: caaHijackedDNS{}},
@@ -972,11 +948,11 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{ripe, apnic},
 				QuorumResult: "2/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: hijackedUA, rir: arin, dns: caaHijackedDNS{}},
-				{ua: remoteUA, rir: ripe},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: ripe, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 		},
 		{
@@ -991,11 +967,11 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{apnic},
 				QuorumResult: "1/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: hijackedUA, rir: arin, dns: caaHijackedDNS{}},
 				{ua: hijackedUA, rir: ripe, dns: caaHijackedDNS{}},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 		},
 		{
@@ -1010,7 +986,7 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{},
 				QuorumResult: "0/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: hijackedUA, rir: arin, dns: caaHijackedDNS{}},
 				{ua: hijackedUA, rir: ripe, dns: caaHijackedDNS{}},
@@ -1027,11 +1003,11 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{ripe, apnic},
 				QuorumResult: "2/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: hijackedUA, rir: arin, dns: caaHijackedDNS{}},
-				{ua: remoteUA, rir: ripe},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: ripe, dns: &caaFakeDNS{}},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 		},
 		{
@@ -1046,11 +1022,11 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{apnic},
 				QuorumResult: "1/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: hijackedUA, rir: arin, dns: caaHijackedDNS{}},
 				{ua: hijackedUA, rir: ripe, dns: caaHijackedDNS{}},
-				{ua: remoteUA, rir: apnic},
+				{ua: remoteUA, rir: apnic, dns: &caaFakeDNS{}},
 			},
 		},
 		{
@@ -1065,7 +1041,7 @@ func TestMultiCAARechecking(t *testing.T) {
 				PassedRIRs:   []string{},
 				QuorumResult: "0/3",
 			},
-			localDNSClient: caaMockDNS{},
+			localDNSClient: &caaFakeDNS{},
 			remoteVAs: []remoteConf{
 				{ua: hijackedUA, rir: arin, dns: caaHijackedDNS{}},
 				{ua: hijackedUA, rir: ripe, dns: caaHijackedDNS{}},
@@ -1095,7 +1071,7 @@ func TestMultiCAARechecking(t *testing.T) {
 				test.AssertNotNil(t, isValidRes.Problem, "IsCAAValidRequest returned nil problem, but should not have")
 				test.AssertContains(t, isValidRes.Problem.Detail, tc.expectedProbSubstring)
 			} else if isValidRes.Problem != nil {
-				test.AssertBoxedNil(t, isValidRes.Problem, "IsCAAValidRequest returned a problem, but should not have")
+				test.AssertBoxedNil(t, isValidRes.Problem, fmt.Sprintf("IsCAAValidRequest returned problem %q, but should not have", isValidRes.Problem.Detail))
 			}
 
 			if tc.expectedProbType != "" {
@@ -1131,7 +1107,7 @@ func TestCAAFailure(t *testing.T) {
 	hs := httpSrv(t, expectedToken, false)
 	defer hs.Close()
 
-	va, _ := setup(hs, "", nil, caaMockDNS{})
+	va, _ := setup(hs, "", nil, &caaFakeDNS{})
 
 	err := va.checkCAA(ctx, identifier.NewDNS("reserved.com"), &caaParams{1, core.ChallengeTypeHTTP01})
 	if err == nil {
@@ -1234,9 +1210,9 @@ func TestSelectCAA(t *testing.T) {
 
 	// A slice of empty caaResults should return nil, "", nil
 	r = []caaResult{
-		{"", false, nil, nil, false, "", nil, nil},
-		{"", false, nil, nil, false, "", nil, nil},
-		{"", false, nil, nil, false, "", nil, nil},
+		{"", false, nil, nil, false, "", "", nil},
+		{"", false, nil, nil, false, "", "", nil},
+		{"", false, nil, nil, false, "", "", nil},
 	}
 	s, err = selectCAA(r)
 	test.Assert(t, s == nil, "set is not nil")
@@ -1245,8 +1221,8 @@ func TestSelectCAA(t *testing.T) {
 	// A slice of caaResults containing an error followed by a CAA
 	// record should return the error
 	r = []caaResult{
-		{"foo.com", false, nil, nil, false, "", nil, errors.New("oops")},
-		{"com", true, []*dns.CAA{&expected}, nil, false, "foo", nil, nil},
+		{"foo.com", false, nil, nil, false, "", "", errors.New("oops")},
+		{"com", true, []*dns.CAA{&expected}, nil, false, "dig", "res", nil},
 	}
 	s, err = selectCAA(r)
 	test.Assert(t, s == nil, "set is not nil")
@@ -1256,26 +1232,24 @@ func TestSelectCAA(t *testing.T) {
 	//  A slice of caaResults containing a good record that precedes an
 	//  error, should return that good record, not the error
 	r = []caaResult{
-		{"foo.com", true, []*dns.CAA{&expected}, nil, false, "foo", nil, nil},
-		{"com", false, nil, nil, false, "", nil, errors.New("")},
+		{"foo.com", true, []*dns.CAA{&expected}, nil, false, "dig", "res", nil},
+		{"com", false, nil, nil, false, "", "", errors.New("")},
 	}
 	s, err = selectCAA(r)
 	test.AssertEquals(t, len(s.issue), 1)
 	test.Assert(t, s.issue[0] == &expected, "Incorrect record returned")
-	test.AssertEquals(t, s.dig, "foo")
 	test.Assert(t, err == nil, "error is not nil")
 
 	// A slice of caaResults containing multiple CAA records should
 	// return the first non-empty CAA record
 	r = []caaResult{
-		{"bar.foo.com", false, []*dns.CAA{}, []*dns.CAA{}, false, "", nil, nil},
-		{"foo.com", true, []*dns.CAA{&expected}, nil, false, "foo", nil, nil},
-		{"com", true, []*dns.CAA{&expected}, nil, false, "bar", nil, nil},
+		{"bar.foo.com", false, []*dns.CAA{}, []*dns.CAA{}, false, "", "", nil},
+		{"foo.com", true, []*dns.CAA{&expected}, nil, false, "dig", "res", nil},
+		{"com", true, []*dns.CAA{&expected}, nil, false, "dig", "res", nil},
 	}
 	s, err = selectCAA(r)
 	test.AssertEquals(t, len(s.issue), 1)
 	test.Assert(t, s.issue[0] == &expected, "Incorrect record returned")
-	test.AssertEquals(t, s.dig, "foo")
 	test.AssertNotError(t, err, "expect nil error")
 }
 
diff --git a/va/dns_account_test.go b/va/dns_account_test.go
index 9e652659f..1098446c4 100644
--- a/va/dns_account_test.go
+++ b/va/dns_account_test.go
@@ -6,14 +6,9 @@ import (
 	"net/netip"
 	"strings"
 	"testing"
-	"time"
 
-	"github.com/jmhodges/clock"
-
-	"github.com/letsencrypt/boulder/bdns"
 	berrors "github.com/letsencrypt/boulder/errors"
 	"github.com/letsencrypt/boulder/identifier"
-	"github.com/letsencrypt/boulder/metrics"
 	"github.com/letsencrypt/boulder/probs"
 	"github.com/letsencrypt/boulder/test"
 )
@@ -85,7 +80,7 @@ func TestDNSAccount01Validation(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			va, _ := setup(nil, "", nil, nil)
+			va, _ := setup(nil, "", nil, &txtFakeDNS{})
 			_, err := va.validateDNSAccount01(ctx, tc.ident, expectedKeyAuthorization, testAccountURI)
 
 			if tc.wantErrMsg != "" {
@@ -109,21 +104,9 @@ func TestDNSAccount01Validation(t *testing.T) {
 }
 
 func TestDNSAccount01ValidationNoServer(t *testing.T) {
-	va, log := setup(nil, "", nil, nil)
-	staticProvider, err := bdns.NewStaticProvider([]string{})
-	test.AssertNotError(t, err, "Couldn't make new static provider")
-
-	va.dnsClient = bdns.NewTest(
-		time.Second*5,
-		staticProvider,
-		metrics.NoopRegisterer,
-		clock.New(),
-		1,
-		"",
-		log,
-		nil)
+	va, _ := setup(nil, "", nil, nil)
 
-	_, err = va.validateDNSAccount01(ctx, identifier.NewDNS("localhost"), expectedKeyAuthorization, testAccountURI)
+	_, err := va.validateDNSAccount01(ctx, identifier.NewDNS("localhost"), expectedKeyAuthorization, testAccountURI)
 	prob := detailedError(err)
 	test.AssertEquals(t, prob.Type, probs.DNSProblem)
 }
diff --git a/va/dns_test.go b/va/dns_test.go
index 1f0a22af8..55a716ea3 100644
--- a/va/dns_test.go
+++ b/va/dns_test.go
@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/jmhodges/clock"
+	"github.com/miekg/dns"
 
 	"github.com/letsencrypt/boulder/bdns"
 	"github.com/letsencrypt/boulder/identifier"
@@ -16,8 +17,91 @@ import (
 	"github.com/letsencrypt/boulder/test"
 )
 
+type txtFakeDNS struct {
+	bdns.Client
+}
+
+func (c *txtFakeDNS) LookupTXT(_ context.Context, hostname string) (*bdns.Result[*dns.TXT], string, error) {
+	// Use the example account-specific label prefix derived from
+	// "https://example.com/acme/acct/ExampleAccount"
+	const accountLabelPrefix = "_ujmmovf2vn55tgye._acme-challenge"
+
+	var wrapTXT = func(txts ...string) (*bdns.Result[*dns.TXT], string, error) {
+		var rrs []*dns.TXT
+		for _, txt := range txts {
+			rrs = append(rrs, &dns.TXT{Txt: []string{txt}})
+		}
+		return &bdns.Result[*dns.TXT]{Final: rrs}, "txtFakeDNS", nil
+	}
+
+	if hostname == accountLabelPrefix+".servfail.com" {
+		// Mirror dns-01 servfail behaviour
+		return nil, "txtFakeDNS", fmt.Errorf("SERVFAIL")
+	}
+	if hostname == accountLabelPrefix+".good-dns01.com" {
+		// Mirror dns-01 good record
+		// base64(sha256("LoqXcYV8q5ONbJQxbmR7SCTNo3tiAXDfowyjxAjEuX0"
+		//               + "." + "9jg46WB3rR_AHD-EBXdN7cBkH1WOu0tA3M9fm21mqTI"))
+		return wrapTXT("LPsIwTo7o8BoG0-vjCyGQGBWSVIPxI-i_X336eUOQZo")
+	}
+	if hostname == accountLabelPrefix+".wrong-dns01.com" {
+		// Mirror dns-01 wrong record
+		return wrapTXT("a")
+	}
+	if hostname == accountLabelPrefix+".wrong-many-dns01.com" {
+		// Mirror dns-01 wrong-many record
+		return wrapTXT("a", "b", "c", "d", "e")
+	}
+	if hostname == accountLabelPrefix+".long-dns01.com" {
+		// Mirror dns-01 long record
+		return wrapTXT("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
+	}
+	if hostname == accountLabelPrefix+".no-authority-dns01.com" {
+		// Mirror dns-01 no-authority good record
+		// base64(sha256("LoqXcYV8q5ONbJQxbmR7SCTNo3tiAXDfowyjxAjEuX0"
+		//               + "." + "9jg46WB3rR_AHD-EBXdN7cBkH1WOu0tA3M9fm21mqTI"))
+		return wrapTXT("LPsIwTo7o8BoG0-vjCyGQGBWSVIPxI-i_X336eUOQZo")
+	}
+	if hostname == accountLabelPrefix+".empty-txts.com" {
+		// Mirror dns-01 zero TXT records
+		return wrapTXT()
+	}
+
+	if hostname == "_acme-challenge.servfail.com" {
+		return nil, "txtFakeDNS", fmt.Errorf("SERVFAIL")
+	}
+	if hostname == "_acme-challenge.good-dns01.com" {
+		// base64(sha256("LoqXcYV8q5ONbJQxbmR7SCTNo3tiAXDfowyjxAjEuX0"
+		//               + "." + "9jg46WB3rR_AHD-EBXdN7cBkH1WOu0tA3M9fm21mqTI"))
+		// expected token + test account jwk thumbprint
+		return wrapTXT("LPsIwTo7o8BoG0-vjCyGQGBWSVIPxI-i_X336eUOQZo")
+	}
+	if hostname == "_acme-challenge.wrong-dns01.com" {
+		return wrapTXT("a")
+	}
+	if hostname == "_acme-challenge.wrong-many-dns01.com" {
+		return wrapTXT("a", "b", "c", "d", "e")
+	}
+	if hostname == "_acme-challenge.long-dns01.com" {
+		return wrapTXT("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
+	}
+	if hostname == "_acme-challenge.no-authority-dns01.com" {
+		// base64(sha256("LoqXcYV8q5ONbJQxbmR7SCTNo3tiAXDfowyjxAjEuX0"
+		//               + "." + "9jg46WB3rR_AHD-EBXdN7cBkH1WOu0tA3M9fm21mqTI"))
+		// expected token + test account jwk thumbprint
+		return wrapTXT("LPsIwTo7o8BoG0-vjCyGQGBWSVIPxI-i_X336eUOQZo")
+	}
+	// empty-txts.com always returns zero TXT records
+	if hostname == "_acme-challenge.empty-txts.com" {
+		return wrapTXT()
+	}
+
+	// Default fallback
+	return wrapTXT("hostname")
+}
+
 func TestDNS01ValidationWrong(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 	_, err := va.validateDNS01(context.Background(), identifier.NewDNS("wrong-dns01.com"), expectedKeyAuthorization)
 	if err == nil {
 		t.Fatalf("Successful DNS validation with wrong TXT record")
@@ -27,7 +111,7 @@ func TestDNS01ValidationWrong(t *testing.T) {
 }
 
 func TestDNS01ValidationWrongMany(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 
 	_, err := va.validateDNS01(context.Background(), identifier.NewDNS("wrong-many-dns01.com"), expectedKeyAuthorization)
 	if err == nil {
@@ -38,7 +122,7 @@ func TestDNS01ValidationWrongMany(t *testing.T) {
 }
 
 func TestDNS01ValidationWrongLong(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 
 	_, err := va.validateDNS01(context.Background(), identifier.NewDNS("long-dns01.com"), expectedKeyAuthorization)
 	if err == nil {
@@ -49,7 +133,7 @@ func TestDNS01ValidationWrongLong(t *testing.T) {
 }
 
 func TestDNS01ValidationFailure(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 
 	_, err := va.validateDNS01(ctx, identifier.NewDNS("localhost"), expectedKeyAuthorization)
 	prob := detailedError(err)
@@ -58,7 +142,7 @@ func TestDNS01ValidationFailure(t *testing.T) {
 }
 
 func TestDNS01ValidationIP(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 
 	_, err := va.validateDNS01(ctx, identifier.NewIP(netip.MustParseAddr("127.0.0.1")), expectedKeyAuthorization)
 	prob := detailedError(err)
@@ -72,7 +156,7 @@ func TestDNS01ValidationInvalid(t *testing.T) {
 		Value: "790DB180-A274-47A4-855F-31C428CB1072",
 	}
 
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 
 	_, err := va.validateDNS01(ctx, notDNS, expectedKeyAuthorization)
 	prob := detailedError(err)
@@ -81,7 +165,7 @@ func TestDNS01ValidationInvalid(t *testing.T) {
 }
 
 func TestDNS01ValidationServFail(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 
 	_, err := va.validateDNS01(ctx, identifier.NewDNS("servfail.com"), expectedKeyAuthorization)
 
@@ -90,7 +174,7 @@ func TestDNS01ValidationServFail(t *testing.T) {
 }
 
 func TestDNS01ValidationNoServer(t *testing.T) {
-	va, log := setup(nil, "", nil, nil)
+	va, log := setup(nil, "", nil, &txtFakeDNS{})
 	staticProvider, err := bdns.NewStaticProvider([]string{})
 	test.AssertNotError(t, err, "Couldn't make new static provider")
 
@@ -110,7 +194,7 @@ func TestDNS01ValidationNoServer(t *testing.T) {
 }
 
 func TestDNS01ValidationOK(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 
 	_, prob := va.validateDNS01(ctx, identifier.NewDNS("good-dns01.com"), expectedKeyAuthorization)
 
@@ -118,7 +202,7 @@ func TestDNS01ValidationOK(t *testing.T) {
 }
 
 func TestDNS01ValidationNoAuthorityOK(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 
 	_, prob := va.validateDNS01(ctx, identifier.NewDNS("no-authority-dns01.com"), expectedKeyAuthorization)
 
diff --git a/va/http_test.go b/va/http_test.go
index c70890864..605acbe03 100644
--- a/va/http_test.go
+++ b/va/http_test.go
@@ -16,6 +16,8 @@ import (
 	"time"
 	"unicode/utf8"
 
+	"github.com/miekg/dns"
+
 	"github.com/letsencrypt/boulder/bdns"
 	"github.com/letsencrypt/boulder/core"
 	berrors "github.com/letsencrypt/boulder/errors"
@@ -27,6 +29,52 @@ import (
 	"testing"
 )
 
+type ipFakeDNS struct {
+	bdns.Client
+}
+
+func (c *ipFakeDNS) LookupA(_ context.Context, hostname string) (*bdns.Result[*dns.A], string, error) {
+	var wrapA = func(ips ...net.IP) (*bdns.Result[*dns.A], string, error) {
+		var rrs []*dns.A
+		for _, ip := range ips {
+			rrs = append(rrs, &dns.A{A: ip})
+		}
+		res := &bdns.Result[*dns.A]{Final: rrs}
+		return res, "ipFakeDNS", nil
+	}
+
+	if strings.HasSuffix(hostname, ".invalid") {
+		return wrapA()
+	}
+	// dual-homed host with an IPv6 and an IPv4 address
+	if hostname == "ipv4.and.ipv6.localhost" {
+		return wrapA(net.IPv4(127, 0, 0, 1))
+	}
+	if hostname == "ipv6.localhost" {
+		return wrapA()
+	}
+	return wrapA(net.IPv4(127, 0, 0, 1))
+}
+
+func (c *ipFakeDNS) LookupAAAA(_ context.Context, hostname string) (*bdns.Result[*dns.AAAA], string, error) {
+	wrapAAAA := func(ips ...net.IP) (*bdns.Result[*dns.AAAA], string, error) {
+		var rrs []*dns.AAAA
+		for _, ip := range ips {
+			rrs = append(rrs, &dns.AAAA{AAAA: ip})
+		}
+		return &bdns.Result[*dns.AAAA]{Final: rrs}, "ipFakeDNS", nil
+	}
+
+	// dual-homed host with an IPv6 and an IPv4 address
+	if hostname == "ipv4.and.ipv6.localhost" {
+		return wrapAAAA(net.IPv6loopback)
+	}
+	if hostname == "ipv6.localhost" {
+		return wrapAAAA(net.IPv6loopback)
+	}
+	return wrapAAAA()
+}
+
 // TestDialerMismatchError tests that using a preresolvedDialer for one host for
 // a dial to another host produces the expected dialerMismatchError.
 func TestDialerMismatchError(t *testing.T) {
@@ -50,15 +98,19 @@ func TestDialerMismatchError(t *testing.T) {
 	test.AssertEquals(t, err.Error(), expectedErr.Error())
 }
 
-// dnsMockReturnsUnroutable is a DNSClient mock that always returns an
-// unroutable address for LookupHost. This is useful in testing connect
-// timeouts.
-type dnsMockReturnsUnroutable struct {
-	*bdns.MockClient
+// unroutableFakeDNS is a DNSClient mock that always returns an
+// unroutable address for LookupA and no results for LookupAAAA. This is useful
+// in testing connect timeouts.
+type unroutableFakeDNS struct {
+	bdns.Client
+}
+
+func (c *unroutableFakeDNS) LookupA(_ context.Context, hostname string) (*bdns.Result[*dns.A], string, error) {
+	return &bdns.Result[*dns.A]{Final: []*dns.A{{A: net.IPv4(64, 112, 117, 254)}}}, "dnsFakeUnroutable", nil
 }
 
-func (mock dnsMockReturnsUnroutable) LookupHost(_ context.Context, hostname string) ([]netip.Addr, bdns.ResolverAddrs, error) {
-	return []netip.Addr{netip.MustParseAddr("64.112.117.254")}, bdns.ResolverAddrs{"dnsMockReturnsUnroutable"}, nil
+func (c *unroutableFakeDNS) LookupAAAA(_ context.Context, hostname string) (*bdns.Result[*dns.AAAA], string, error) {
+	return nil, "dnsFakeUnroutable", errors.New("SERVFAIL")
 }
 
 // TestDialerTimeout tests that the preresolvedDialer's DialContext
@@ -67,7 +119,7 @@ func (mock dnsMockReturnsUnroutable) LookupHost(_ context.Context, hostname stri
 // the appropriate "Timeout during connect" error message, which helps clients
 // distinguish between firewall problems and server problems.
 func TestDialerTimeout(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &unroutableFakeDNS{})
 	// Timeouts below 50ms tend to be flaky.
 	va.singleDialTimeout = 50 * time.Millisecond
 
@@ -76,7 +128,6 @@ func TestDialerTimeout(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), ctxTimeout)
 	defer cancel()
 
-	va.dnsClient = dnsMockReturnsUnroutable{&bdns.MockClient{}}
 	// NOTE(@jsha): The only method I've found so far to trigger a connect timeout
 	// is to connect to an unrouteable IP address. This usually generates
 	// a connection timeout, but will rarely return "Network unreachable" instead.
@@ -126,8 +177,6 @@ func TestHTTPTransport(t *testing.T) {
 }
 
 func TestHTTPValidationTarget(t *testing.T) {
-	// NOTE(@cpu): See `bdns/mocks.go` and the mock `LookupHost` function for the
-	// hostnames used in this test.
 	testCases := []struct {
 		Name          string
 		Ident         identifier.ACMEIdentifier
@@ -137,7 +186,7 @@ func TestHTTPValidationTarget(t *testing.T) {
 		{
 			Name:          "No IPs for DNS identifier",
 			Ident:         identifier.NewDNS("always.invalid"),
-			ExpectedError: berrors.DNSError("No valid IP addresses found for always.invalid"),
+			ExpectedError: berrors.DNSError("no valid A records found for always.invalid; no valid AAAA records found for always.invalid"),
 		},
 		{
 			Name:        "Only IPv4 addrs for DNS identifier",
@@ -173,7 +222,7 @@ func TestHTTPValidationTarget(t *testing.T) {
 		exampleQuery = "my-path=was&my=own"
 	)
 
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &ipFakeDNS{})
 	for _, tc := range testCases {
 		t.Run(tc.Name, func(t *testing.T) {
 			target, err := va.newHTTPValidationTarget(
@@ -410,7 +459,7 @@ func TestExtractRequestTarget(t *testing.T) {
 }
 
 func TestSetupHTTPValidation(t *testing.T) {
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &ipFakeDNS{})
 
 	mustTarget := func(t *testing.T, host string, port int, path string) *httpValidationTarget {
 		target, err := va.newHTTPValidationTarget(
@@ -472,7 +521,7 @@ func TestSetupHTTPValidation(t *testing.T) {
 				URL:               "http://ipv4.and.ipv6.localhost/yellow/brick/road",
 				AddressesResolved: []netip.Addr{netip.MustParseAddr("::1"), netip.MustParseAddr("127.0.0.1")},
 				AddressUsed:       netip.MustParseAddr("::1"),
-				ResolverAddrs:     []string{"MockClient"},
+				ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 			},
 			ExpectedDialer: &preresolvedDialer{
 				ip:      netip.MustParseAddr("::1"),
@@ -490,7 +539,7 @@ func TestSetupHTTPValidation(t *testing.T) {
 				URL:               "https://ipv4.and.ipv6.localhost/yellow/brick/road",
 				AddressesResolved: []netip.Addr{netip.MustParseAddr("::1"), netip.MustParseAddr("127.0.0.1")},
 				AddressUsed:       netip.MustParseAddr("::1"),
-				ResolverAddrs:     []string{"MockClient"},
+				ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 			},
 			ExpectedDialer: &preresolvedDialer{
 				ip:      netip.MustParseAddr("::1"),
@@ -799,8 +848,8 @@ func TestFetchHTTP(t *testing.T) {
 
 	// Setup VAs. By providing the testSrv to setup the VA will use the testSrv's
 	// randomly assigned port as its HTTP port.
-	vaIPv4, _ := setup(testSrvIPv4, "", nil, nil)
-	vaIPv6, _ := setup(testSrvIPv6, "", nil, nil)
+	vaIPv4, _ := setup(testSrvIPv4, "", nil, &ipFakeDNS{})
+	vaIPv6, _ := setup(testSrvIPv6, "", nil, &ipFakeDNS{})
 
 	// We need to know the randomly assigned HTTP port for testcases as well
 	httpPortIPv4 := getPort(testSrvIPv4)
@@ -827,7 +876,7 @@ func TestFetchHTTP(t *testing.T) {
 				URL:               url,
 				AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 				AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-				ResolverAddrs:     []string{"MockClient"},
+				ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 			})
 	}
 
@@ -848,7 +897,7 @@ func TestFetchHTTP(t *testing.T) {
 				URL:               url,
 				AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 				AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-				ResolverAddrs:     []string{"MockClient"},
+				ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 			})
 	}
 
@@ -871,7 +920,7 @@ func TestFetchHTTP(t *testing.T) {
 			Ident: identifier.NewDNS("always.invalid"),
 			Path:  "/.well-known/whatever",
 			ExpectedProblem: probs.DNS(
-				"No valid IP addresses found for always.invalid"),
+				"no valid A records found for always.invalid; no valid AAAA records found for always.invalid"),
 			// There are no validation records in this case because the base record
 			// is only constructed once a URL is made.
 			ExpectedRecords: nil,
@@ -890,7 +939,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/timeout",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -925,7 +974,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/redir-bad-proto",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -943,7 +992,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/redir-bad-port",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -959,7 +1008,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/redir-bare-ipv4",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 				{
 					Hostname:          "127.0.0.1",
@@ -982,7 +1031,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://ipv6.localhost/redir-bare-ipv6",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("::1")},
 					AddressUsed:       netip.MustParseAddr("::1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 				{
 					Hostname:          "::1",
@@ -1006,7 +1055,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/redir-path-too-long",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -1023,7 +1072,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/bad-status-code",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -1040,7 +1089,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/303-see-other",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -1058,7 +1107,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/resp-too-big",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -1075,7 +1124,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://ipv6.localhost/ok",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("::1")},
 					AddressUsed:       netip.MustParseAddr("::1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -1092,7 +1141,7 @@ func TestFetchHTTP(t *testing.T) {
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("::1"), netip.MustParseAddr("127.0.0.1")},
 					// The first validation record should have used the IPv6 addr
 					AddressUsed:   netip.MustParseAddr("::1"),
-					ResolverAddrs: []string{"MockClient"},
+					ResolverAddrs: []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 				{
 					Hostname:          "ipv4.and.ipv6.localhost",
@@ -1101,7 +1150,7 @@ func TestFetchHTTP(t *testing.T) {
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("::1"), netip.MustParseAddr("127.0.0.1")},
 					// The second validation record should have used the IPv4 addr as a fallback
 					AddressUsed:   netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs: []string{"MockClient"},
+					ResolverAddrs: []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -1117,7 +1166,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/ok",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -1133,7 +1182,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/redir-uppercase-publicsuffix",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 				{
 					Hostname:          "example.com",
@@ -1141,7 +1190,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/ok",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -1162,7 +1211,7 @@ func TestFetchHTTP(t *testing.T) {
 					URL:               "http://example.com/printf-verbs",
 					AddressesResolved: []netip.Addr{netip.MustParseAddr("127.0.0.1")},
 					AddressUsed:       netip.MustParseAddr("127.0.0.1"),
-					ResolverAddrs:     []string{"MockClient"},
+					ResolverAddrs:     []string{"ipFakeDNS", "ipFakeDNS"},
 				},
 			},
 		},
@@ -1298,7 +1347,7 @@ func TestHTTPBadPort(t *testing.T) {
 	hs := httpSrv(t, expectedToken, false)
 	defer hs.Close()
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	// Pick a random port between 40000 and 65000 - with great certainty we won't
 	// have an HTTP server listening on this port and the test will fail as
@@ -1342,7 +1391,7 @@ func TestHTTPKeyAuthorizationFileMismatch(t *testing.T) {
 	})
 	hs.Start()
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 	_, err := va.validateHTTP01(ctx, identifier.NewDNS("localhost.com"), expectedToken, expectedKeyAuthorization)
 
 	if err == nil {
@@ -1358,7 +1407,7 @@ func TestHTTP(t *testing.T) {
 	hs := httpSrv(t, expectedToken, false)
 	defer hs.Close()
 
-	va, log := setup(hs, "", nil, nil)
+	va, log := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateHTTP01(ctx, identifier.NewDNS("localhost.com"), expectedToken, expectedKeyAuthorization)
 	if err != nil {
@@ -1423,7 +1472,7 @@ func TestHTTPIPv6(t *testing.T) {
 	hs := httpSrv(t, expectedToken, true)
 	defer hs.Close()
 
-	va, log := setup(hs, "", nil, nil)
+	va, log := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateHTTP01(ctx, identifier.NewIP(netip.MustParseAddr("::1")), expectedToken, expectedKeyAuthorization)
 	if err != nil {
@@ -1436,7 +1485,7 @@ func TestHTTPTimeout(t *testing.T) {
 	hs := httpSrv(t, expectedToken, false)
 	defer hs.Close()
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	started := time.Now()
 	timeout := 250 * time.Millisecond
@@ -1464,7 +1513,7 @@ func TestHTTPTimeout(t *testing.T) {
 func TestHTTPRedirectLookup(t *testing.T) {
 	hs := httpSrv(t, expectedToken, false)
 	defer hs.Close()
-	va, log := setup(hs, "", nil, nil)
+	va, log := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateHTTP01(ctx, identifier.NewDNS("localhost.com"), pathMoved, ka(pathMoved))
 	if err != nil {
@@ -1526,7 +1575,7 @@ func TestHTTPRedirectLookup(t *testing.T) {
 func TestHTTPRedirectLoop(t *testing.T) {
 	hs := httpSrv(t, expectedToken, false)
 	defer hs.Close()
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, prob := va.validateHTTP01(ctx, identifier.NewDNS("localhost"), "looper", ka("looper"))
 	if prob == nil {
@@ -1537,7 +1586,7 @@ func TestHTTPRedirectLoop(t *testing.T) {
 func TestHTTPRedirectUserAgent(t *testing.T) {
 	hs := httpSrv(t, expectedToken, false)
 	defer hs.Close()
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 	va.userAgent = rejectUserAgent
 
 	_, prob := va.validateHTTP01(ctx, identifier.NewDNS("localhost"), pathMoved, ka(pathMoved))
@@ -1573,7 +1622,7 @@ func TestValidateHTTP(t *testing.T) {
 	hs := httpSrv(t, token, false)
 	defer hs.Close()
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, prob := va.validateHTTP01(ctx, identifier.NewDNS("localhost"), token, ka(token))
 	test.Assert(t, prob == nil, "validation failed")
@@ -1583,7 +1632,7 @@ func TestLimitedReader(t *testing.T) {
 	token := core.NewToken()
 
 	hs := httpSrv(t, "012345\xff67890123456789012345678901234567890123456789012345678901234567890123456789", false)
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 	defer hs.Close()
 
 	_, err := va.validateHTTP01(ctx, identifier.NewDNS("localhost"), token, ka(token))
@@ -1654,7 +1703,7 @@ func TestHTTPHostHeader(t *testing.T) {
 
 			// Setup VA. By providing the testSrv to setup the VA will use the
 			// testSrv's randomly assigned port as its HTTP port.
-			va, _ := setup(testSrv, "", nil, nil)
+			va, _ := setup(testSrv, "", nil, &ipFakeDNS{})
 
 			var got string
 			_, _, _ = va.processHTTPValidation(ctx, tc.Ident, "/ok")
diff --git a/va/tlsalpn_test.go b/va/tlsalpn_test.go
index 31de4c2ad..ec6af5cd8 100644
--- a/va/tlsalpn_test.go
+++ b/va/tlsalpn_test.go
@@ -24,7 +24,6 @@ import (
 
 	"github.com/prometheus/client_golang/prometheus"
 
-	"github.com/letsencrypt/boulder/bdns"
 	"github.com/letsencrypt/boulder/core"
 	"github.com/letsencrypt/boulder/identifier"
 	"github.com/letsencrypt/boulder/probs"
@@ -139,7 +138,7 @@ func slowTLSSrv() *httptest.Server {
 
 func TestTLSALPNTimeoutAfterConnect(t *testing.T) {
 	hs := slowTLSSrv()
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	timeout := 50 * time.Millisecond
 	ctx, cancel := context.WithTimeout(context.Background(), timeout)
@@ -176,7 +175,7 @@ func TestTLSALPNTimeoutAfterConnect(t *testing.T) {
 
 func TestTLSALPN01DialTimeout(t *testing.T) {
 	hs := slowTLSSrv()
-	va, _ := setup(hs, "", nil, dnsMockReturnsUnroutable{&bdns.MockClient{}})
+	va, _ := setup(hs, "", nil, &unroutableFakeDNS{})
 	started := time.Now()
 
 	timeout := 50 * time.Millisecond
@@ -225,7 +224,7 @@ func TestTLSALPN01DialTimeout(t *testing.T) {
 func TestTLSALPN01Refused(t *testing.T) {
 	hs := testTLSALPN01Srv(t)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	// Take down validation server and check that validation fails.
 	hs.Close()
@@ -244,7 +243,7 @@ func TestTLSALPN01Refused(t *testing.T) {
 func TestTLSALPN01TalkingToHTTP(t *testing.T) {
 	hs := testTLSALPN01Srv(t)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	// Make the server only speak HTTP.
 	httpOnly := httpSrv(t, "", false)
@@ -273,7 +272,7 @@ func brokenTLSSrv() *httptest.Server {
 func TestTLSError(t *testing.T) {
 	hs := brokenTLSSrv()
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	if err == nil {
@@ -289,7 +288,7 @@ func TestTLSError(t *testing.T) {
 func TestDNSError(t *testing.T) {
 	hs := brokenTLSSrv()
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("always.invalid"), expectedKeyAuthorization)
 	if err == nil {
@@ -366,7 +365,7 @@ func TestCertNames(t *testing.T) {
 func TestTLSALPN01SuccessDNS(t *testing.T) {
 	hs := testTLSALPN01Srv(t)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	res, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	if err != nil {
@@ -385,7 +384,7 @@ func TestTLSALPN01SuccessIPv4(t *testing.T) {
 	cert := testTLSCert(nil, []net.IP{net.ParseIP("127.0.0.1")}, []pkix.Extension{testACMEExt})
 	hs := tlsalpn01SrvWithCert(t, cert, 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	res, err := va.validateTLSALPN01(ctx, identifier.NewIP(netip.MustParseAddr("127.0.0.1")), expectedKeyAuthorization)
 	if err != nil {
@@ -404,7 +403,7 @@ func TestTLSALPN01SuccessIPv6(t *testing.T) {
 	cert := testTLSCert(nil, []net.IP{net.ParseIP("::1")}, []pkix.Extension{testACMEExt})
 	hs := tlsalpn01SrvWithCert(t, cert, 0, true)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	res, err := va.validateTLSALPN01(ctx, identifier.NewIP(netip.MustParseAddr("::1")), expectedKeyAuthorization)
 	if err != nil {
@@ -432,7 +431,7 @@ func TestTLSALPN01ObsoleteFailure(t *testing.T) {
 	cert := testTLSCert([]string{"expected"}, nil, []pkix.Extension{acmeExtension(IdPeAcmeIdentifierV1Obsolete, expectedKeyAuthorization)})
 	hs := tlsalpn01SrvWithCert(t, cert, 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	test.AssertNotNil(t, err, "expected validation to fail")
@@ -445,7 +444,7 @@ func TestValidateTLSALPN01BadChallenge(t *testing.T) {
 	cert := testTLSCert([]string{"expected"}, nil, []pkix.Extension{acmeExtension(IdPeAcmeIdentifier, badKeyAuthorization)})
 	hs := tlsalpn01SrvWithCert(t, cert, 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	if err == nil {
@@ -466,7 +465,7 @@ func TestValidateTLSALPN01BadChallenge(t *testing.T) {
 func TestValidateTLSALPN01BrokenSrv(t *testing.T) {
 	hs := brokenTLSSrv()
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	if err == nil {
@@ -489,7 +488,7 @@ func TestValidateTLSALPN01UnawareSrv(t *testing.T) {
 	}
 	hs.StartTLS()
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	if err == nil {
@@ -522,7 +521,7 @@ func TestValidateTLSALPN01MalformedExtnValue(t *testing.T) {
 	for _, badExt := range badExtensions {
 		acmeCert := testTLSCert([]string{"expected"}, nil, []pkix.Extension{badExt})
 		hs := tlsalpn01SrvWithCert(t, acmeCert, 0, false)
-		va, _ := setup(hs, "", nil, nil)
+		va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 		_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 		hs.Close()
@@ -562,7 +561,7 @@ func TestTLSALPN01TLSVersion(t *testing.T) {
 		// Create a server that only negotiates the given TLS version
 		hs := tlsalpn01SrvWithCert(t, cert, tc.version, false)
 
-		va, _ := setup(hs, "", nil, nil)
+		va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 		_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 		if !tc.expectError {
@@ -587,7 +586,7 @@ func TestTLSALPN01WrongName(t *testing.T) {
 	// Create a cert with a different name from what we're validating
 	hs := tlsalpn01SrvWithCert(t, testACMECert([]string{"incorrect"}), 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -599,7 +598,7 @@ func TestTLSALPN01WrongIPv4(t *testing.T) {
 	cert := testTLSCert(nil, []net.IP{net.ParseIP("10.10.10.10")}, []pkix.Extension{testACMEExt})
 	hs := tlsalpn01SrvWithCert(t, cert, 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewIP(netip.MustParseAddr("127.0.0.1")), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -611,7 +610,7 @@ func TestTLSALPN01WrongIPv6(t *testing.T) {
 	cert := testTLSCert(nil, []net.IP{net.ParseIP("::2")}, []pkix.Extension{testACMEExt})
 	hs := tlsalpn01SrvWithCert(t, cert, 0, true)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewIP(netip.MustParseAddr("::1")), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -622,7 +621,7 @@ func TestTLSALPN01ExtraNames(t *testing.T) {
 	// Create a cert with two names when we only want to validate one.
 	hs := tlsalpn01SrvWithCert(t, testACMECert([]string{"expected", "extra"}), 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -633,7 +632,7 @@ func TestTLSALPN01WrongIdentType(t *testing.T) {
 	// Create a cert with an IP address encoded as a name.
 	hs := tlsalpn01SrvWithCert(t, testACMECert([]string{"127.0.0.1"}), 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewIP(netip.MustParseAddr("127.0.0.1")), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -644,7 +643,7 @@ func TestTLSALPN01TooManyIdentTypes(t *testing.T) {
 	// Create a cert with both a name and an IP address when we only want to validate one.
 	hs := tlsalpn01SrvWithCert(t, testTLSCert([]string{"expected"}, []net.IP{net.ParseIP("127.0.0.1")}, []pkix.Extension{testACMEExt}), 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -702,7 +701,7 @@ func TestTLSALPN01NotSelfSigned(t *testing.T) {
 
 	hs := tlsalpn01SrvWithCert(t, acmeCert, 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err = va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -720,7 +719,7 @@ func TestTLSALPN01NotSelfSigned(t *testing.T) {
 
 	hs = tlsalpn01SrvWithCert(t, acmeCert, 0, false)
 
-	va, _ = setup(hs, "", nil, nil)
+	va, _ = setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err = va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -759,7 +758,7 @@ func TestTLSALPN01ExtraIdentifiers(t *testing.T) {
 
 	hs := tlsalpn01SrvWithCert(t, acmeCert, tls.VersionTLS12, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err = va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -782,7 +781,7 @@ func TestTLSALPN01ExtraSANs(t *testing.T) {
 	extensions := []pkix.Extension{testACMEExt, subjectAltName, subjectAltName}
 	hs := tlsalpn01SrvWithCert(t, testTLSCert([]string{"expected"}, nil, extensions), 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err = va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -797,7 +796,7 @@ func TestTLSALPN01ExtraAcmeExtensions(t *testing.T) {
 	extensions := []pkix.Extension{testACMEExt, testACMEExt}
 	hs := tlsalpn01SrvWithCert(t, testTLSCert([]string{"expected"}, nil, extensions), 0, false)
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.NewDNS("expected"), expectedKeyAuthorization)
 	test.AssertError(t, err, "validation should have failed")
@@ -861,7 +860,7 @@ func TestTLSALPN01BadIdentifier(t *testing.T) {
 	hs := httpSrv(t, expectedToken, false)
 	defer hs.Close()
 
-	va, _ := setup(hs, "", nil, nil)
+	va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 	_, err := va.validateTLSALPN01(ctx, identifier.ACMEIdentifier{Type: "smime", Value: "dobber@bad.horse"}, expectedKeyAuthorization)
 	test.AssertError(t, err, "Server accepted a hypothetical S/MIME identifier")
@@ -938,7 +937,7 @@ func TestTLSALPN01ServerName(t *testing.T) {
 			hs.StartTLS()
 			defer hs.Close()
 
-			va, _ := setup(hs, "", nil, nil)
+			va, _ := setup(hs, "", nil, &ipFakeDNS{})
 
 			// The actual test happens in the tlsConfig.GetCertificate function,
 			// which the validation will call and depend on for its success.
diff --git a/va/va_test.go b/va/va_test.go
index 196ca97dc..273c563e2 100644
--- a/va/va_test.go
+++ b/va/va_test.go
@@ -116,7 +116,7 @@ func isNonLoopbackReservedIP(ip netip.Addr) error {
 //
 // If remoteVAs is nil, this builds a VA that acts like a remote (and does not
 // perform multi-perspective validation). Otherwise it acts like a primary.
-func setup(srv *httptest.Server, userAgent string, remoteVAs []RemoteVA, mockDNSClientOverride bdns.Client) (*ValidationAuthorityImpl, *blog.Mock) {
+func setup(srv *httptest.Server, userAgent string, remoteVAs []RemoteVA, fakeDNSClient bdns.Client) (*ValidationAuthorityImpl, *blog.Mock) {
 	features.Reset()
 	fc := clock.NewFake()
 
@@ -133,8 +133,13 @@ func setup(srv *httptest.Server, userAgent string, remoteVAs []RemoteVA, mockDNS
 		perspective = "example perspective " + core.RandomString(4)
 	}
 
+	dnsClient := fakeDNSClient
+	if dnsClient == nil {
+		dnsClient = &bdns.MockClient{}
+	}
+
 	va, err := NewValidationAuthorityImpl(
-		&bdns.MockClient{Log: logger},
+		dnsClient,
 		remoteVAs,
 		userAgent,
 		"letsencrypt.org",
@@ -146,15 +151,12 @@ func setup(srv *httptest.Server, userAgent string, remoteVAs []RemoteVA, mockDNS
 		"",
 		isNonLoopbackReservedIP,
 		time.Second,
+		true,
 	)
 	if err != nil {
 		panic(fmt.Sprintf("Failed to create validation authority: %v", err))
 	}
 
-	if mockDNSClientOverride != nil {
-		va.dnsClient = mockDNSClientOverride
-	}
-
 	// Adjusting industry regulated ACME challenge port settings is fine during
 	// testing
 	if srv != nil {
@@ -166,8 +168,8 @@ func setup(srv *httptest.Server, userAgent string, remoteVAs []RemoteVA, mockDNS
 	return va, logger
 }
 
-func setupRemote(srv *httptest.Server, userAgent string, mockDNSClientOverride bdns.Client, perspective, rir string) RemoteClients {
-	rva, _ := setup(srv, userAgent, nil, mockDNSClientOverride)
+func setupRemote(srv *httptest.Server, userAgent string, fakeDNSClient bdns.Client, perspective, rir string) RemoteClients {
+	rva, _ := setup(srv, userAgent, nil, fakeDNSClient)
 	rva.perspective = perspective
 	rva.rir = rir
 
@@ -222,9 +224,9 @@ func setupRemotes(confs []remoteConf, srv *httptest.Server) []RemoteVA {
 	return remoteVAs
 }
 
-func setupWithRemotes(srv *httptest.Server, userAgent string, remotes []remoteConf, mockDNSClientOverride bdns.Client) (*ValidationAuthorityImpl, *blog.Mock) {
+func setupWithRemotes(srv *httptest.Server, userAgent string, remotes []remoteConf, fakeDNSClient bdns.Client) (*ValidationAuthorityImpl, *blog.Mock) {
 	remoteVAs := setupRemotes(remotes, srv)
-	return setup(srv, userAgent, remoteVAs, mockDNSClientOverride)
+	return setup(srv, userAgent, remoteVAs, fakeDNSClient)
 }
 
 type multiSrv struct {
@@ -313,7 +315,7 @@ func TestNewValidationAuthorityImplWithDuplicateRemotes(t *testing.T) {
 	}
 
 	_, err := NewValidationAuthorityImpl(
-		&bdns.MockClient{Log: blog.NewMock()},
+		&bdns.MockClient{},
 		remoteVAs,
 		"user agent 1.0",
 		"letsencrypt.org",
@@ -325,6 +327,7 @@ func TestNewValidationAuthorityImplWithDuplicateRemotes(t *testing.T) {
 		"",
 		isNonLoopbackReservedIP,
 		time.Second,
+		true,
 	)
 	test.AssertError(t, err, "NewValidationAuthorityImpl allowed duplicate remote perspectives")
 	test.AssertContains(t, err.Error(), "duplicate remote VA perspective \"dadaist\"")
@@ -334,19 +337,19 @@ func TestPerformValidationWithMismatchedRemoteVAPerspectives(t *testing.T) {
 	t.Parallel()
 
 	mismatched1 := RemoteVA{
-		RemoteClients: setupRemote(nil, "", nil, "dadaist", arin),
+		RemoteClients: setupRemote(nil, "", &txtFakeDNS{}, "dadaist", arin),
 		Perspective:   "baroque",
 		RIR:           arin,
 	}
 	mismatched2 := RemoteVA{
-		RemoteClients: setupRemote(nil, "", nil, "impressionist", ripe),
+		RemoteClients: setupRemote(nil, "", &txtFakeDNS{}, "impressionist", ripe),
 		Perspective:   "minimalist",
 		RIR:           ripe,
 	}
 	remoteVAs := setupRemotes([]remoteConf{{rir: ripe}}, nil)
 	remoteVAs = append(remoteVAs, mismatched1, mismatched2)
 
-	va, mockLog := setup(nil, "", remoteVAs, nil)
+	va, mockLog := setup(nil, "", remoteVAs, &txtFakeDNS{})
 	req := createValidationRequest(identifier.NewDNS("good-dns01.com"), core.ChallengeTypeDNS01)
 	res, _ := va.DoDCV(context.Background(), req)
 	test.AssertNotNil(t, res.GetProblem(), "validation succeeded with mismatched remote VA perspectives")
@@ -357,19 +360,19 @@ func TestPerformValidationWithMismatchedRemoteVARIRs(t *testing.T) {
 	t.Parallel()
 
 	mismatched1 := RemoteVA{
-		RemoteClients: setupRemote(nil, "", nil, "dadaist", arin),
+		RemoteClients: setupRemote(nil, "", &txtFakeDNS{}, "dadaist", arin),
 		Perspective:   "dadaist",
 		RIR:           ripe,
 	}
 	mismatched2 := RemoteVA{
-		RemoteClients: setupRemote(nil, "", nil, "impressionist", ripe),
+		RemoteClients: setupRemote(nil, "", &txtFakeDNS{}, "impressionist", ripe),
 		Perspective:   "impressionist",
 		RIR:           arin,
 	}
 	remoteVAs := setupRemotes([]remoteConf{{rir: ripe}}, nil)
 	remoteVAs = append(remoteVAs, mismatched1, mismatched2)
 
-	va, mockLog := setup(nil, "", remoteVAs, nil)
+	va, mockLog := setup(nil, "", remoteVAs, &txtFakeDNS{})
 	req := createValidationRequest(identifier.NewDNS("good-dns01.com"), core.ChallengeTypeDNS01)
 	res, _ := va.DoDCV(context.Background(), req)
 	test.AssertNotNil(t, res.GetProblem(), "validation succeeded with mismatched remote VA perspectives")
@@ -387,7 +390,7 @@ func TestValidateMalformedChallenge(t *testing.T) {
 
 func TestPerformValidationInvalid(t *testing.T) {
 	t.Parallel()
-	va, _ := setup(nil, "", nil, nil)
+	va, _ := setup(nil, "", nil, &txtFakeDNS{})
 
 	req := createValidationRequest(identifier.NewDNS("foo.com"), core.ChallengeTypeDNS01)
 	res, _ := va.DoDCV(context.Background(), req)
@@ -404,7 +407,7 @@ func TestPerformValidationInvalid(t *testing.T) {
 func TestInternalErrorLogged(t *testing.T) {
 	t.Parallel()
 
-	va, mockLog := setup(nil, "", nil, nil)
+	va, mockLog := setup(nil, "", nil, &ipFakeDNS{})
 
 	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Millisecond)
 	defer cancel()
@@ -419,7 +422,7 @@ func TestInternalErrorLogged(t *testing.T) {
 func TestPerformValidationValid(t *testing.T) {
 	t.Parallel()
 
-	va, mockLog := setup(nil, "", nil, nil)
+	va, mockLog := setup(nil, "", nil, &txtFakeDNS{})
 
 	// create a challenge with well known token
 	req := createValidationRequest(identifier.NewDNS("good-dns01.com"), core.ChallengeTypeDNS01)
@@ -447,7 +450,7 @@ func TestPerformValidationValid(t *testing.T) {
 func TestPerformValidationWildcard(t *testing.T) {
 	t.Parallel()
 
-	va, mockLog := setup(nil, "", nil, nil)
+	va, mockLog := setup(nil, "", nil, &txtFakeDNS{})
 
 	// create a challenge with well known token
 	req := createValidationRequest(identifier.NewDNS("*.good-dns01.com"), core.ChallengeTypeDNS01)
@@ -503,9 +506,9 @@ func TestMultiVA(t *testing.T) {
 			// With local and all remote VAs working there should be no problem.
 			Name: "Local and remote VAs OK",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
-				{ua: pass, rir: ripe},
-				{ua: pass, rir: apnic},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
+				{ua: pass, rir: ripe, dns: &ipFakeDNS{}},
+				{ua: pass, rir: apnic, dns: &ipFakeDNS{}},
 			},
 			PrimaryUA: pass,
 		},
@@ -513,9 +516,9 @@ func TestMultiVA(t *testing.T) {
 			// If the local VA fails everything should fail
 			Name: "Local VA bad, remote VAs OK",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
-				{ua: pass, rir: ripe},
-				{ua: pass, rir: apnic},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
+				{ua: pass, rir: ripe, dns: &ipFakeDNS{}},
+				{ua: pass, rir: apnic, dns: &ipFakeDNS{}},
 			},
 			PrimaryUA:        fail,
 			ExpectedProbType: string(probs.UnauthorizedProblem),
@@ -524,8 +527,8 @@ func TestMultiVA(t *testing.T) {
 			// If one out of three remote VAs fails with an internal err it should succeed
 			Name: "Local VA ok, 1/3 remote VA internal err",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
-				{ua: pass, rir: ripe},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
+				{ua: pass, rir: ripe, dns: &ipFakeDNS{}},
 				{ua: pass, rir: apnic, impl: brokenVA},
 			},
 			PrimaryUA: pass,
@@ -534,7 +537,7 @@ func TestMultiVA(t *testing.T) {
 			// If two out of three remote VAs fail with an internal err it should fail
 			Name: "Local VA ok, 2/3 remote VAs internal err",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
 				{ua: pass, rir: ripe, impl: brokenVA},
 				{ua: pass, rir: apnic, impl: brokenVA},
 			},
@@ -547,10 +550,10 @@ func TestMultiVA(t *testing.T) {
 			// If one out of five remote VAs fail with an internal err it should succeed
 			Name: "Local VA ok, 1/5 remote VAs internal err",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
-				{ua: pass, rir: ripe},
-				{ua: pass, rir: apnic},
-				{ua: pass, rir: lacnic},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
+				{ua: pass, rir: ripe, dns: &ipFakeDNS{}},
+				{ua: pass, rir: apnic, dns: &ipFakeDNS{}},
+				{ua: pass, rir: lacnic, dns: &ipFakeDNS{}},
 				{ua: pass, rir: afrinic, impl: brokenVA},
 			},
 			PrimaryUA: pass,
@@ -559,9 +562,9 @@ func TestMultiVA(t *testing.T) {
 			// If two out of five remote VAs fail with an internal err it should fail
 			Name: "Local VA ok, 2/5 remote VAs internal err",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
-				{ua: pass, rir: ripe},
-				{ua: pass, rir: apnic},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
+				{ua: pass, rir: ripe, dns: &ipFakeDNS{}},
+				{ua: pass, rir: apnic, dns: &ipFakeDNS{}},
 				{ua: pass, rir: arin, impl: brokenVA},
 				{ua: pass, rir: ripe, impl: brokenVA},
 			},
@@ -574,10 +577,10 @@ func TestMultiVA(t *testing.T) {
 			// If two out of six remote VAs fail with an internal err it should succeed
 			Name: "Local VA ok, 2/6 remote VAs internal err",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
-				{ua: pass, rir: ripe},
-				{ua: pass, rir: apnic},
-				{ua: pass, rir: lacnic},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
+				{ua: pass, rir: ripe, dns: &ipFakeDNS{}},
+				{ua: pass, rir: apnic, dns: &ipFakeDNS{}},
+				{ua: pass, rir: lacnic, dns: &ipFakeDNS{}},
 				{ua: pass, rir: afrinic, impl: brokenVA},
 				{ua: pass, rir: arin, impl: brokenVA},
 			},
@@ -587,9 +590,9 @@ func TestMultiVA(t *testing.T) {
 			// If three out of six remote VAs fail with an internal err it should fail
 			Name: "Local VA ok, 4/6 remote VAs internal err",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
-				{ua: pass, rir: ripe},
-				{ua: pass, rir: apnic},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
+				{ua: pass, rir: ripe, dns: &ipFakeDNS{}},
+				{ua: pass, rir: apnic, dns: &ipFakeDNS{}},
 				{ua: pass, rir: lacnic, impl: brokenVA},
 				{ua: pass, rir: afrinic, impl: brokenVA},
 				{ua: pass, rir: arin, impl: brokenVA},
@@ -603,9 +606,9 @@ func TestMultiVA(t *testing.T) {
 			// With only one working remote VA there should be a validation failure
 			Name: "Local VA and one remote VA OK",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
-				{ua: fail, rir: ripe},
-				{ua: fail, rir: apnic},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
+				{ua: fail, rir: ripe, dns: &ipFakeDNS{}},
+				{ua: fail, rir: apnic, dns: &ipFakeDNS{}},
 			},
 			PrimaryUA:           pass,
 			ExpectedProbType:    string(probs.UnauthorizedProblem),
@@ -615,9 +618,9 @@ func TestMultiVA(t *testing.T) {
 			// If one remote VA cancels, it should succeed
 			Name: "Local VA and one remote VA OK, one cancelled VA",
 			Remotes: []remoteConf{
-				{ua: pass, rir: arin},
+				{ua: pass, rir: arin, dns: &ipFakeDNS{}},
 				{ua: pass, rir: ripe, impl: cancelledVA},
-				{ua: pass, rir: apnic},
+				{ua: pass, rir: apnic, dns: &ipFakeDNS{}},
 			},
 			PrimaryUA: pass,
 		},
@@ -637,9 +640,9 @@ func TestMultiVA(t *testing.T) {
 			// With the local and remote VAs seeing diff problems, we expect a problem.
 			Name: "Local and remote VA differential",
 			Remotes: []remoteConf{
-				{ua: fail, rir: arin},
-				{ua: fail, rir: ripe},
-				{ua: fail, rir: apnic},
+				{ua: fail, rir: arin, dns: &ipFakeDNS{}},
+				{ua: fail, rir: ripe, dns: &ipFakeDNS{}},
+				{ua: fail, rir: apnic, dns: &ipFakeDNS{}},
 			},
 			PrimaryUA:           pass,
 			ExpectedProbType:    string(probs.UnauthorizedProblem),
@@ -656,7 +659,7 @@ func TestMultiVA(t *testing.T) {
 			defer ms.Close()
 
 			// Configure a primary VA with testcase remote VAs.
-			localVA, mockLog := setupWithRemotes(ms.Server, tc.PrimaryUA, tc.Remotes, nil)
+			localVA, mockLog := setupWithRemotes(ms.Server, tc.PrimaryUA, tc.Remotes, &ipFakeDNS{})
 
 			// Perform all validations
 			res, _ := localVA.DoDCV(ctx, req)
@@ -707,15 +710,15 @@ func TestMultiVALogging(t *testing.T) {
 	t.Parallel()
 
 	remoteConfs := []remoteConf{
-		{ua: pass, rir: arin},
-		{ua: pass, rir: ripe},
-		{ua: pass, rir: apnic},
+		{ua: pass, rir: arin, dns: &ipFakeDNS{}},
+		{ua: pass, rir: ripe, dns: &ipFakeDNS{}},
+		{ua: pass, rir: apnic, dns: &ipFakeDNS{}},
 	}
 
 	ms := httpMultiSrv(t, expectedToken, map[string]bool{pass: true, fail: false})
 	defer ms.Close()
 
-	va, _ := setupWithRemotes(ms.Server, pass, remoteConfs, nil)
+	va, _ := setupWithRemotes(ms.Server, pass, remoteConfs, &ipFakeDNS{})
 	req := createValidationRequest(identifier.NewDNS("letsencrypt.org"), core.ChallengeTypeHTTP01)
 	res, err := va.DoDCV(ctx, req)
 	test.Assert(t, res.Problem == nil, fmt.Sprintf("validation failed with: %#v", res.Problem))