draft-pauly-httpbis-alias-proxy-status: consider including rrset(s) for IP addresses

[enygren]

One of the use-cases for draft-pauly-httpbis-alias-proxy-status may be for influencing connection coalescing behaviors. Since some clients use "is the IP address that the proxy is connecting to overlapping with the rrset(s) used by other connections" having the full IP address rrset lists for A and AAAA responses might be worthwhile.

At a minimum, we may want to allow listing all IP addresses tried before establishing the connection. (eg, a TCP proxy might implement happy eyeballs and/or fail-over between multiple IP addresses.) Knowing which others were tried but not used (when possible) might help for some of the abuse/use cases.

On the other hand, both of these might add unneeded complexity.

[tfpauly]

I think this is something that should go to future work, personally — knowing the fuller set of RRs is something clients would need, but probably should have some client opt-in and negotiation for