North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: is reverse dns required? (policy question)
* william(at)elan.net <[email protected]> [2004-12-04 16:14]: > On Sat, 4 Dec 2004, Henning Brauer wrote: > > Thus we propose expanding the reverse DNS tree with a subdomain with > > the well known name > > > > _srv > > > > This subdomain MAY be inserted at any level in the DNS tree for IPv4 > > IN-ADDR.ARPA reverse zones. For IPv6, to limit the number of DNS > > queries, _srv is only queried at the /128 (host), /64 (subnet) and / > > 32 (site) level. That way it can either provide information for a > > specific IP address or for a whole network block. More specific > > information takes precedence over information found closer to the top > > of the tree. > > So if I want to check on 127.1.2.3, I first do lookup on > _srv.3.2.1.127.IN-ADDR.ARPA > if that does not give any answer, I'll have to do lookup on > _srv.2.1.127.IN-ADDR.ARPA > if that does not give any answer, I'll have to do lookup on > _srv.1.127.IN-ADDR.ARPA > And if that does not work, I still have to do lookup on > _srv.127.IN-ADDR.ARPA that is how it works. > Is that how you expect it to work? If that is so, I do not like it > because it forces to do these multiple lookups. these lookups are cheap, and with increasing deployment I expect the the vast majority of lookups to have matches on /32 (1st query) or /24 (2nd query). but anyway, these lookups are reasonably cheap. -- Henning Brauer, BS Web Services, http://bsws.de [email protected] - [email protected] Unix is very simple, but it takes a genius to understand the simplicity. (Dennis Ritchie)
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