> On Tue, Jun 26, 2007 at 02:44:41PM +1000, Mark Andrews wrote: > > > > [RFC1912] suggests that it is an operational or > > > configuration error not to have matching PTR and A records. > > > Every address should have a PTR which gives the cannonical name > > of the host which in turn has a matching address record. > > > > It is a bad idea to say for the to be a PTR for every ownername > > of a address record. It doesn't take too many A records, which > > all have the same address, before you exceed the DNS protocol > > limits with multiple PTR records. > > The proposed text is intended to go in section 2, which is background > for the document. I believe that the draft is actually a softening of > the language in RFC1912, partly for the reasons you state. There is > text consitent with what you are saying in section 3.3: > > It is possible for there to be multiple PTRs at a single reverse tree > node. In extreme cases, these multiple PTRs could cause a DNS > response to exceed the UDP limit, and fall back to TCP. Such a case > could be one where the advantages of reverse mapping are exceeded by > the disadvantages of the additional burden. This may be of > particular significance for "mass virtual hosting" systems, where > many hostnames are associated with a single IP. > > Now that I look at this, however, it's not really correct, given > EDNS0. So, I have two questions: > > 1. Does the text from section 3.3 address your concerns about the > proposed additional text in section 2 ("Background")? > > 2. Can you (or anyone else) suggest a better way of phrasing the > "multiple PTR" paragraph to account for EDNS0 as well?
EDNS really doesn't change it. You can still exceed the limits of what can be put into EDNS/UDP packets. You can also exceed what can be put into a {E}DNS/TCP message. I've seen the later occur plenty of times. > Thanks, > A > > -- > Andrew Sullivan 204-4141 Yonge Street > Afilias Canada Toronto, Ontario Canada > <[EMAIL PROTECTED]> M2P 2A8 > jabber: [EMAIL PROTECTED] +1 416 646 3304 x4110 > > _______________________________________________ > DNSOP mailing list > DNSOP@ietf.org > https://www1.ietf.org/mailman/listinfo/dnsop -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: [EMAIL PROTECTED] _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www1.ietf.org/mailman/listinfo/dnsop