* william(at)elan.net <william@elan.net> [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 hb@bsws.de - henning@openbsd.org Unix is very simple, but it takes a genius to understand the simplicity. (Dennis Ritchie)