On Mon, Mar 04, 2013 at 12:31:08PM -0600, Blake Hudson wrote:
> KSB wrote the following on 3/4/2013 12:13 PM:
> >On 2013.03.04. 20:06, Blake Hudson wrote:
> >>Just hoping to get a consensus on this. Postfix is stating that a 
> >>host (in fact several hosts from the same ISP) does not have 
> >>rDNS, because our DNS (Bind 9.8) returns SERVFAIL when looking up 
> >>a PTR record for it. The IP in question is 63.171.0.212. From my

See RFC 2317.

> >>perspective, this IP does not have a PTR record and as such does 
> >>not have proper rDNS. Other tools (including older versions of 
> >>bind) might say otherwise; What do you say?
> >>*
> >Seems very, very strage... but probably this is allowed, anybody knows?
> >
> >;; QUESTION SECTION:
> >;212.0.171.63.in-addr.arpa.     IN      PTR
> >
> >;; ANSWER SECTION:
> >212.0.171.63.in-addr.arpa. 86400 IN     CNAME
> >63.171.0.212.cust.lkq.sprintlink.net.
> >63.171.0.212.cust.lkq.sprintlink.net. 86400 IN PTR mail1.lkqcorp.com.

It's fine. As to why your named is returning SERVFAIL, that is 
another issue. Obviously a SERVFAIL will prevent it from being 
resolved. I get the SERVFAIL as well:

Mar  4 12:51:36 chestnut named[1811]: error (chase DS servers) 
resolving 'cust.lkq.sprintlink.net/DS/IN': 144.228.254.10#53
Mar  4 12:51:36 chestnut named[1811]: error (insecurity proof failed) 
resolving 'lkq.sprintlink.net/NS/IN': 144.228.255.10#53
Mar  4 12:51:36 chestnut named[1811]: error (insecurity proof failed) 
resolving 'lkq.sprintlink.net/NS/IN': 206.228.179.10#53
Mar  4 12:51:36 chestnut named[1811]: error (insecurity proof failed) 
resolving 'lkq.sprintlink.net/NS/IN': 144.228.254.10#53
Mar  4 12:51:36 chestnut named[1811]: error (no valid DS) resolving 
'63.171.0.212.cust.lkq.sprintlink.net/PTR/IN': 144.228.254.10#53

This is a problem with the DNSSEC signing.

> OK, so we ask for a PTR on 212.0.171.63.in-addr.arpa and instead
> receive a CNAME (with additional). Did anyone notice that the CNAME
> does not resolve?
> 
> --
> 
> # dig @ns1-auth.sprintlink.net 63.171.0.212.cust.lkq.sprintlink.net

You're doing a default query type, for "A".

> ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6_3.4 <<>>
> @ns1-auth.sprintlink.net 63.171.0.212.cust.lkq.sprintlink.net
> ; (2 servers found)
> ;; global options: +cmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7207

NOERROR means that the name exists, but there is no data of the 
requested type, A. It's wrong to assume that all names in the DNS 
should have A records.

> ;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
> ;; WARNING: recursion requested but not available
> 
> ;; QUESTION SECTION:
> ;63.171.0.212.cust.lkq.sprintlink.net. IN A
> 
> ;; AUTHORITY SECTION:
> cust.lkq.sprintlink.net. 7200   IN      SOA ns1-auth.sprintlink.net.
> dns-admin.sprint.net. 2010080301 43200 3600 2419200 7200
> 
> ;; Query time: 50 msec
> ;; SERVER: 206.228.179.10#53(206.228.179.10)
> ;; WHEN: Mon Mar  4 12:04:25 2013
> ;; MSG SIZE  rcvd: 116
> 
> --

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