How to a dig -x to return A records and CNAMES

[Barry Margolin]

In article <do9p4c$1v2s$1 at sf1.isc.org>,
 "Beast" <adamnealis at yahoo.co.uk> wrote:

> Hi,
> 
> If this is a FAQ I apologise, but I couldn't find an example.
> 
> I have a "forward" domain mydom.net, in which I have an A record and a
> CNAME like this.
> 
> tc23.test.mydom.net. 1800  IN      CNAME   sol41.mydom.net.
> sol41.mydom.net.       1800    IN      A       10.144.114.170
> 
> I have corresponding PTRs in another zone file:
> 
> 170.114.144.10 IN   PTR  sol41.mydom.net.
> 170.114.144.10 IN   PTR  tc23.test.mydom.net.
> 
> So when I dig, I get
> 
> $ dig +short -x 10.144.114.170
> tc23.test.mydom.net.
> sol41.mydom.net.
> 
> Which is cool, but a chore to maintain as I have to add PTRs for A
> records and CNAMEs.
> 
> Is there a way to configure things such that one need only add a PTR
> for the A record and the dig above returns both A and CNAMEs?

PTR records are only supposed to point to primary names, i.e. names with 
A records.  You shouldn't have the PTR record that points to the alias, 
and you shouldn't expect the reverse lookup to return it.

In general, there's no good reason for a PTR lookup to return more than 
one name.  Most applications that do reverse lookups only use the first 
one that's returned.  See the recent thread "Random DNS-reply" for the 
confusion that can result.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***
*** PLEASE don't copy me on replies, I'll read them in the group ***