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.