[Galaxy Tab S2 Original Android Development] Deltadroid:
DNSCrypt automatically downloads a signed list of approved dns servers in a file called public-resolvers.md (which is defined in DNSCrypt's primary configuration file, dnscrypt-proxy.toml). Currently, DNSCrypt's configuration is setup to only use DNS servers from scaleway-fr, google, yandex, and cloudflare that are in the approved list of dns servers. Here is where the line is that defines what groups of dns servers to use in the approved list:

https://github.com/syphyr/dnscrypt_...er/etc/dnscrypt-proxy/dnscrypt-proxy.toml#L32

DNSCrypt will then check the speed of the defined groups of DNS Servers and automatically use the fastest one, as shown in the log snippet below. This is why DNSCrypt is generally faster than other DNS methods that just assign a single DNS Server to use.

Sep 9 18:52:01 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:01] [NOTICE] dnscrypt-proxy is waiting for at least one server to be reachable
Sep 9 18:52:13 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:13] [NOTICE] [yandex] OK (DNSCrypt) - rtt: 1962ms
Sep 9 18:52:17 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:17] [NOTICE] [google] OK (DoH) - rtt: 760ms
Sep 9 18:52:20 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:20] [NOTICE] [cloudflare] OK (DoH) - rtt: 755ms
Sep 9 18:52:22 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:22] [NOTICE] [scaleway-fr] OK (DNSCrypt) - rtt: 1469ms
Sep 9 18:52:22 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:22] [NOTICE] Sorted latencies:
Sep 9 18:52:22 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:22] [NOTICE] - 755ms cloudflare
Sep 9 18:52:22 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:22] [NOTICE] - 760ms google
Sep 9 18:52:22 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:22] [NOTICE] - 1469ms scaleway-fr
Sep 9 18:52:22 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:22] [NOTICE] - 1962ms yandex
Sep 9 18:52:22 droid dnscrypt-proxy[1141]: [2020-09-09 18:52:22] [NOTICE] Server with the lowest initial latency: cloudflare (rtt: 755ms)

So, currently DNSCrypt is configured to use the fastest DNS Server from scaleway-fr, google, yandex, and cloudflare.

Also, Ad Blocking is enabled from the following two lines in DNSCrypt's configuration file:

https://github.com/syphyr/dnscrypt_...r/etc/dnscrypt-proxy/dnscrypt-proxy.toml#L467

and

https://github.com/syphyr/dnscrypt_...r/etc/dnscrypt-proxy/dnscrypt-proxy.toml#L523

Commenting out those two lines in the configuration file would disable ad blocking in DNSCrypt.

Currently, there is no easy way to allow for all the various configurations and I would suggest just remounting the system as writable, editing DNSCrypt's configuration file, and turning the service off and back on again to restart it. There are a lot of different ways DNSCrypt can be configured, such as telling it to use Anonymous DNS paths, for example:

https://github.com/syphyr/dnscrypt_...r/etc/dnscrypt-proxy/dnscrypt-proxy.toml#L671

It may be worth testing out different DNSCrypt configurations and find out what works best for you, although, I think the current configuration provides the fastest DNS. If DNSCrypt is configured to sort though all of the approved DNS Servers in public-resolvers.md, instead of just scaleway-fr, google, yandex, and cloudflare, it becomes pretty slow on startup, which is why is it configured to only use DNS servers from a few select domains.

There is also a second DNSCrypt configuration file that is used instead when tor is enabled in the developer settings. https://github.com/syphyr/dnscrypt_...er/etc/dnscrypt-proxy/dnscrypt-proxy-tor.toml. So, if that option is enabled, then you want to edit this configuration file instead of the other one.