[dns-wg] Re: [address-policy-wg] Policy Change Request - Allow address allocations for anycast DNS operation

Not having seen the whole discussion thread, it's a bit hard to make
sense of what's been said. However it appears to be that someone is
saying that the need for anycasting (and more specifically special
address allocations for anycast name servers) can be discounted if
ENDS0 was more widely used. This is a flawed argument IMO. As Peter
has said, resolvers that aren't EDNS0-aware will still be pounding on
the parent zone's name servers. [They're also much more likely to be
the resolvers that are misconfigured to go to the root to reverse
lookup RFC1918 addresses, don't implement negative caching and so
on....] Simply adding more NS records and glue in the parent zone's
delegation for a child zone is no help. For one thing, most name
server implementations have a limit on the number of name servers they
can handle for a delegation. Adding extra NS records is even less help
when those servers have IPv6 addresses => yet bigger DNS payloads. In
fact adding extra servers and/or IPv6 addresses may be worse because
there's an increased likelihood of truncated responses getting sent to
these non-EDNS0 resolvers, resulting in retried queries over TCP. Nasty.

Aside from these DNS protocol issues, there are plenty of other good
reasons for deploying anycasting for important DNS infrastructure.
That's why lots of the root and TLD name server operators are doing
this already. Ironically, these include the NCC's root name server.
Anycasting provides increased robustness, extra redundancy, improved
performance, better scalability, extra capacity/throughput, defence in
depth from DDoS attacks, etc, etc. Anycasting isn't going to go away
even if all the world's DNS software implemented EDNS0. Anycasting is
a fact of life. And it will become more prominent in future.

So if the address policy WG is reluctant to endorse special address
allocations for DNS anycasting, I'd ask them to reconsider. If it
helps, we could ask the DNS WG to discuss the issue and perhaps make a
recommendation to the address policy WG.