Reverse DNS on non-network .0 addresses

McNutt, Justin M. McNuttJ at missouri.edu
Thu Jan 31 13:17:30 UTC 2002


> I'm trying to get reverse DNS working on two .0 addresses=20
> that aren't designated as network IP's.  I am currently=20
> allocated a /22 network: xxx.xxx.40.0 - xxx.xxx.43.0  I am=20
> unable to propigate reverse DNS for xxx.xxx.41.0 and=20
> xxx.xxx.42.0 even though they aren't used as a network IP's. =20
> I do use forward DNS on those IP's and interface aliasing=20
> with the .0's works fine.  Am I incorrect in assuming that=20
> the 41.0 and 42.0 addresses are *not* network identifiers? =20
> My subnet mask for all of the IP's in the range is=20
> 255.255.252.0 with the network address being 40.0 and the=20
> broadcast address being 43.0
>=20
> Any suggestions?

Let's begin with a confirmation that what you're trying to do is =
possible in BIND:

C:\>nslookup 128.206.93.0
Server:  ns3.missouri.edu
Address:  128.206.10.3

Name:    mu-093000.dhcp.missouri.edu
Address:  128.206.93.0

Yup.  You can do it.  Therefore, we only have to worry about why it =
isn't working.

Please post the full IP address for XX.XX.42.0 so we can look at the =
records and see what's wrong.  If the addresses are in a private =
network, please post the relevant parts of the zone file so we can look =
at the problem (we need at least the SOA record for =
42.XX.XX.in-addr.arpa and the PTR record for the .0 address).

You are correct about network identifiers, though.  Which IP addresses =
are networks and which ones are hosts is determined by the subnet mask, =
not the numbers or DNS.  In my network, 128.206.130.4 is a network, but =
128.206.93.0 is a host.  :-)

--J


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