reverse DNS resolution...

Philip M. Gollucci pgollucci at
Mon Oct 22 14:51:43 PDT 2007

Eric F Crist wrote:
> Hey folks,
> We're trying to get reverse DNS resolution for a block of IPs
> (private).  We've had the 10.x network working great at the office
> for quite some time now, but I'm having a problem getting the
> 172.30.x network to work.
> Typing 'host <ip>' returns a valid result, however output from who,
> as well as other network services (IRC, apache) only see the IP.  Is
> there something I'm missing?
> Thanks for the pointers!
Well, your DNS needs to be authoritative for both forward and reverse.
If you are trying to do this for less then a /24 block the zone files
get messy quick because of the 8bit boundaries.  You seem to be trying
to do this for a /16.  I'll bet you're missing the named.conf entries
and related reverse zone files:

Odds are you'll want to have zones:

zone "" {
  type master;
  file "master/
  notify yes;
zone "" {
  ;; or slave config since you'll have more than 1 ns
  type slave;
  file "slave/";
  masters { x.y.z.a; };

Or some larger splits of that.

You're going to have give me a netmask for more help.

$TTL 3600       ; 1 hour   IN SOA  ns1.rws. admin.Z. (
                                2007101800 ; Serial
                                10800      ; refresh (3 hours)
                                3600       ; retry (1 hour)
                                3600       ; expire (1 hour)
                                86400      ; minimum (1 day)
                        NS      ns1.Z.
1                       PTR     router.Z.

Philip M. Gollucci (philip at c:323.219.4708 o:703.749.9295x206
Senior System Admin - Riderway, Inc. /
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love like you'll never get hurt,
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