Performance Issues - PTR Records

Fri Nov 4 16:28:14 UTC 2011

paul4004> It is entirely possible they have it pointed to their
paul4004> non-existent or broken DNS.  Given current best practices, I
paul4004> see no reason not to assign a generic
paul4004> x.x.x.x-dynamic.customer.isp.com DNS across their netblock.

It's already been pointed out that lame delegations are more likely
problems for many. But the "we'll just pre-fill in-addr to avoid
problems" isn't going to work for ip6.arpa. If anyone has enough
hardware to serve the zone for a /48 (64k * 4bil * 4bil *
bytes-in-record), I'd love to see it. :)

We need to get web and app folks to stop counting on
ip6.arpa/in-addr.arpa as a validation of trustworthiness. PTR make some
sense for validating servers, MTAs, etc. and it's handy for traceroute
but it was never a great tool and it's getting less useful with time.