With this in mind, then is it just a failing of BIND that it only recognizes the first PTR record and disregards the rest (unlike the typical A record format used for round-robin) ? << Yes, I know what kind of flack that this will lead to, but the logic isn't that wierd... Karyn
10.2. PTR records
Confusion about canonical names has lead to a belief that a PTR record should have exactly one RR in its RRSet. This is incorrect, the relevant section of RFC1034 (section 3.6.2) indicates that the value of a PTR record should be a canonical name. That is, it should not be an alias. There is no implication in that section that only one PTR record is permitted for a name. No such restriction should be inferred.
Note that while the value of a PTR record must not be an alias, there is no requirement that the process of resolving a PTR record not encounter any aliases. The label that is being looked up for a PTR value might have a CNAME record. That is, it might be an alias. The value of that CNAME RR, if not another alias, which it should not be, will give the location where the PTR record is found. That record gives the result of the PTR type lookup. This final result, the value of the PTR RR, is the label which must not be an alias.
-- Greg A. Woods
+1 416 218-0098 VE3TCP <gwoods@acm.org> <robohack!woods> Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>
[ On Friday, August 18, 2000 at 14:08:49 (-0700), Karyn Ulriksen wrote: ]
Subject: RE: lame delegations
With this in mind, then is it just a failing of BIND that it only recognizes the first PTR record and disregards the rest (unlike the typical A record format used for round-robin) ?
Unless I misunderstand what you mean, my version of BIND (8.2.2p3) doesn't do that. $ host -a 2.254.92.204.in-addr.arpa 2.254.92.204.in-addr.arpa PTR most.weird.com 2.254.92.204.in-addr.arpa PTR mail.weird.com I don't think it round-robins them though (that's the order they appear in my zone file and several queries in a row always return them in that order -- I've not read the code recently so I don't remember for sure), because normally you don't want to round-robin them, and if you did you wouldn't be able to distinguish between the primary host and its aliases with the BIND resolver library: $ host -a 204.92.254.2 Name: most.weird.com Address: 204.92.254.2 Aliases: mail.weird.com (The "primary", or "official" hostname comes from the "h_name" field of "struct hostent", which is returned by gethostbyaddr() and friends.)
<< Yes, I know what kind of flack that this will lead to, but the logic isn't that wierd...
I can't give you any flack about multiple PTRs, I use them too! :-) -- Greg A. Woods +1 416 218-0098 VE3TCP <gwoods@acm.org> <robohack!woods> Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>
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