Original text:
Replace the IP address of the ICE candidate with its mDNS hostname and provide the candidate to the web application. <del> An ICE agent can implement this procedure in any way so long as it produces equivalent results to this procedure. </del>  <del> An implementation may for instance pre-register mDNS hostnames by executing steps 3 to 5 and prepopulate an ICE agent accordingly.  By doing so, only step 6 of the above procedure will be executed at the time of gathering candidates. </del>  An implementation may also detect that mDNS is not supported by the <del> available network interfaces.  The ICE agent may skip steps 2 and 3 </del>  and directly decide to not expose the host candidate. This procedure ensures that an mDNS name is used to replace only one

Reviewer comments:
I think this is good to go, will plan to land at EOD.
Does it obfuscate, conceal, or obscure local IP addresses? My vote is for conceal.
Conceal/concealment sgtm.
As noted in , we don't need to use the same term in every case, but the terms should have the same meaning. conceal and hide are fairly synonymous, but conceal and obfuscate have slightly different meanings.
This section is largely normative, so it might make more sense to put some parts from it immediately after Principle, namely the various adjustments to the technique that need to be considered (TURN, IPv6, stats) Things where we merely provide discussion (e.g., session monitoring) rather than normative guidance could remain in the privacy section.
Due to their different sensitivity and lifetime.
If we add this indication, do we also need to clarify the use case for lite ICE agents?
What did you have in mind?
{{#gathering}} starts with "For any host candidate gathered by an ICE agent as part of {{RFC8445}} section 5.1.1," it seems the place we need to revise to resolve this issue. I was thinking of allowing ICE lite implementation to skip the mDNS wrapping, since lite agents only use host candidates (8445, section 2.5). The lite implementation is however not required restricted to ICE agents that always have public IPs from my reading of that section, but rather an alternative to simplify the implementation when possible. So I am still not sure if it makes sense to say lite ICE can be exempted from wrapping; or instead indicating mDNS wrapping can be skipped if host candidates are equivalent to srflx candidates, and automatically the intended use of lite ICE satisfies this condition.
Right, the public IPs exception probably covers this. also indicates that this is really for web browsers, which are not allowed to implement ICE Lite.
Started writing this up today, but realized it's not totally clear how this should work. The idea would be to use STUN to figure out if an IP is public or not, but... Should we wait to hand out the mDNS candidate until we determine if the IP is private (i.e., STUN finishes)? Should we not hand out the mDNS candidate if we get a srflx candidate that shows the IP is not private? If we hand out the mDNS candidate and then get a srflx candidate that matches the local IP, should we make that a host candidate? Once we learn an IP is not public, should we cache that for future ICE gathering sessions (i.e., not give out mDNS candidates?) The easiest thing would probably be to recommend handing out the mDNS and srflx candidates as usual, but allow implementations to skip mDNS for IPs it has learned are public. (Except for RFC1918 addresses, which would always be treated as private.)
Partially addressed in , will probably include some additional clarifying text once it lands
The rest LGTM

Revised text:
Replace the IP address of the ICE candidate with its mDNS hostname and provide the candidate to the web application.  <ins> ICE agents can implement this procedure in any way as long as it produces equivalent results.  An implementation may for instance pre- register mDNS hostnames by executing steps 3 to 6 and prepopulate an ICE agent accordingly.  By doing so, only step 7 of the above procedure will be executed at the time of gathering candidates. </ins>  <ins> ICE agents may also decide that certain local IP addresses are safe to expose.  This may be because the ICE agent has a priori knowledge that the address is in fact public, or because the agent has made a policy decision to not conceal certain types of IP addresses (e.g., those with built-in privacy protections) as a calculated choice to improve connectivity.  This topic is discussed further in {#privacy} below. </ins> An implementation may also detect that mDNS is not supported by the  <ins> available network interfaces.  The ICE agent may skip steps 3 and 4 </ins> and directly decide to not expose the host candidate. This procedure ensures that an mDNS name is used to replace only one