DNS woes (was Re: 50Hz vs 60Hz fixed drive speed ?)

Then why aren't all the hosts I see no rDNS for in China nullrouted? I think you missed the "de-facto" part of what I said. What you said sounds like a de-jure requirement, and anyone hwo actually looks for rDNS many places will see that there is no such de-facto requirement. And, it would have to be ICANN; ARIN has no jurisdiction outside North America. In practice, it simply isn't enforced - witness China - which is why I say that de-facto it's nonexistent at present. Then why aren't they nullrouted? This comes back to the difference between the de-jure rqeuirement you cite and the observance of current reality, which is that there is no such requirement in practice. As additional PTR records, or as names to which CNAMEs, pointing to the real PTR-owning names, are attached? Either one could reasonably be called aliases, and there is a huge difference. Now I'm confused. I can't figure out what you're describing. The only RFC I'm aware of that could be behind the "RFC sanctioned mechanism" is 2317, but that one describes the CNAME way, and nobody competent enough to get that right is likely to put in A records for the intermediate CNAMEs. What is the address of the mailhost in question? That way I can just poke at the DNS and see what's really there.... /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B