rDNS naming conventions (was: Re: SORBS Contact)

Thu Aug 10 19:44:03 UTC 2006

on Thu, Aug 10, 2006 at 08:55:37PM +0530, Suresh Ramasubramanian wrote:
> 
> On 8/10/06, Steven Champeon <schampeo at hesketh.com> wrote:
> >redundancy "bigisp-foo-bar-baz.dyn.bigisp.net". Worst among those who
> >actually provide rDNS in SE Asia is probably tm.net.my, who name all of
> >their customer PTRs 'tm.net.my'. Hm. Maybe encoding the IP in the PTR
> 
> There's at least one vietnamese ISP that has / had till recently set
> "localhost" as rDNS for all their IPs.

IIRC, that was fpt.vn; they replaced 'localhost' with the incredibly
useful:

adsl-pool-xxx.fpt.vn
adsl-fix-xxx.fpt.vn
dialup-xxx.fpt.vn
adsl-dynamic-pool-xxx.fpt.vn
\d+-\d+-\d+-xxx-dynamic.hcm.fpt.vn
host-\d+-xx.hcm.fpt.vn
\d+-\d+-\d+-xxx-dynamic.hcm.fpt.vn

Yes, the 'xxx's are literals. e.g., 

$ host 210.245.14.143
143.14.245.210.in-addr.arpa domain name pointer dialup-xxx.fpt.vn.

Or it may have been hnpt.com.vn, who replaced it with e.g.,

adsl.hnpt.com.vn

Again, not terribly useful for tracking leakage via NATs.

$ host 203.210.213.149
149.213.210.203.in-addr.arpa domain name pointer adsl.hnpt.com.vn.

But hey, at least they *have* rDNS, I suppose that's something.

I agree that judgements based entirely on rDNS are troublesome. So,
too, are the side effects of chemotherapy. But we're trying to save
the patient before the miracle cures arrive, and right now email is
very, very sick indeed. And rDNS is a useful tool especially in a
scoring-based environment.

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