Domain and subdomain from the same IP

[Will Yardley]

Dr. Muhammad Masroor Ali wrote:
 
> I am trying to serve a domain say, mydept.myco.com and its parent
> domain myco.com 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
245.85.209.in-addr.arpa
i've removed / reordered some entries

$TTL 2h
@       IN      SOA     ns.newdream.net. hostmaster.dreamhost.com. (
                         2001100603 ; serial
                         3h ; refresh
                         30m ; retry
                         3w ; expire
                         5m) ; minimum
        IN      NS      ns.newdream.net.
        IN      NS      ns2.newdream.net.
        IN      NS      ns3.newdream.net.
        IN      PTR     ip-209-85-245-0.g.di.dreamhost.com.
1       IN      PTR     ip-209-85-245-1.g.di.dreamhost.com.
2       IN      PTR     ip-209-85-245-2.g.di.dreamhost.com.
[...]
215     IN      PTR     dydimus.dreamhost.com.
216     IN      PTR     bang.dreamhost.com.
... and so on

and the named.conf entry:
zone "245.85.209.in-addr.arpa" {
        type master;
        file "/var/named/dh.generated/2/245.85.209.in-addr.arpa";
};


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