Domain and subdomain from the same IP

Will Yardley william+dns at
Sat Oct 6 18:32:56 UTC 2001

Dr. Muhammad Masroor Ali wrote:
> I am trying to serve a domain say, and its parent
> domain from the same static IP. While other settings are more
> or less clear to me, I can not seem to understand how to set up the
> reverse zone lookup.

do you own the entire netblock for this IP (ie the whole class C or
class B)?  if you have < 254 IP addresses than you need to make
arrangements with your ISP to either delegate reverse DNS to you for
these IP addresses or add the appropriate PTR entries to the zone file
for that netblock (the latter being simpler if you are not going to
change stuff a lot).

here's an example with bits of a reverse zone file for
i've removed / reordered some entries

$TTL 2h
@       IN      SOA (
                         2001100603 ; serial
                         3h ; refresh
                         30m ; retry
                         3w ; expire
                         5m) ; minimum
        IN      NS
        IN      NS
        IN      NS
        IN      PTR
1       IN      PTR
2       IN      PTR
215     IN      PTR
216     IN      PTR
... and so on

and the named.conf entry:
zone "" {
        type master;
        file "/var/named/dh.generated/2/";

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