|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: lame delegations
On Fri, 18 Aug 2000, Gary E. Miller wrote: > RFC 1912, Sec 2.1: > > " Make sure your PTR and A records match. For every IP address, there > should be a matching PTR record in the in-addr.arpa domain. If a > host is multi-homed, (more than one IP address) make sure that all IP > addresses have a corresponding PTR record (not just the first one). > Failure to have matching PTR and A records can cause loss of Internet > services similar to not being registered in the DNS at all. Also, > PTR records must point back to a valid A record, not a alias defined > by a CNAME. It is highly recommended that you use some software > which automates this checking, or generate your DNS data from a > database which automatically creates consistent data." > > I have yet to hear a convincing argument why this RFC should be > ignored. I have seen many problems when this is ignored. > This raises a question that I've had for some time. This says that a "PTR record must point to a valid A record, not an alias defined by a CNAME". RFC 1035, Sec. 3.3.12 says that the PTRDNAME is a "<domain-name> which points to some location in the domain name space" and that "PTR records cause no additional section processing". Since RFC 1035, Sec. 3.3 states that a <domain-name> is just a label, and says nothing that the label has to have a corresponding A record. Since RFC 1912 is informational and does not update RFC 1035, it would seem that a PTR record does *not* have to point to a host that resolves. No? Am I getting lost in the fine print? Am I missing a later RFC that clarifies this? -- Alex Kamantauskas [email protected]
|