reverse lookup on local IP (

Richard Barnes rbarnes at
Fri Nov 12 17:13:36 UTC 1999

10.X.X.X is a non-routable IP address.

Unless you ran a local DNS deamon and have a entry, you
should not be able to find any entires for a 10.x.x.x IP address.

I say "local DNS deamon" because there is absolutely no reason for an ISP to
do reverse DNS lookups on any non-routable IP addresses. (10.x.x.x,
172.x.x.x, and 192.168.x.x)

so to answer your question:

>Shouldn't I be able to resolve to a name?


your connection to the ISP is probably some form of NAT translation.
Meaning your caching server has two IP addresses on it (a real one, and the
non-routable one,  anytime one of you workstations requests an
Internet resource (webpage, newsgroup, etc.) your caching server does the
actualy request for you, and then sends the returned info to the client who
originally requested it.

Is there a reason you want reverse DNS setup?  If you are getting errors
when surfing, indicating that reverse DNS is not enabled, perhaps you should
contact you ISP and have them setup a reverse lookup entry for the IP
address of your caching server (the real, routable one).

-----Original Message-----
From: alex <alexkrowitz at>
Newsgroups: comp.os.linux.networking;,comp.protocols.dns.bind
To: comp-protocols-dns-bind at
<comp-protocols-dns-bind at>
Date: Friday, November 12, 1999 11:27 AM
Subject: reverse lookup on local IP (

>Does anyone know whether I should be able to nslookup my local IP?
>I have a small network set up as 10.x.x.x, and dial in to an ISP.
>My caching nameserver is on
>If I try (from the machine) to nslookup, I get:
>-> Server:  localhost
>-> Address:
>-> *** localhost can't find Non-existent host/domain
>Shouldn't I be able to resolve to a name?
>Here's /etc/resolv.conf:
>order hosts,bind
>multi on
>Here's /etc/hosts:
>       localhost     
>     mydnshost
>     otherhost
>Thanks for your help.
>Alex <alexkrowitz at>
>Sent via
>Before you buy.

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