SUMMARY: (no solution) : reverse lookup fails

From: Rae, Scott (
Date: Thu Jul 13 2000 - 08:02:45 CDT

Dear list,

        I got several very useful replies to my question, which is copied at
the bottom of this message. Unfortunately I was not able to resolve the
problem. After spending a few hours on it, the user said that things were
working well enough for now (they don't NEED to do reverse lookups at
present), and my boss said I had to go and do other things anyway....

        Many thanks to Robert Hayne, Todd Herr, Philip Ordinario, Claudio
Cuestas, Adam and Christine Levin, Dave McFerren, Rodney Wines, Richard
Butler, Hoang Nguyen and Peter Gutmann for their help.

        The main suggestions were:

1. You've got to update the serial number, by incrementing it, each
time you update a named file, and then signal your named process
to re-read your named file by HUP'ing the named process:

   kill -HUP <named process PID>

A good format to use for your serial numbers is:


where YYYY is the year the file was changed
        MM is the month
        DD is the date
        XX is a two digit number (you probably won't make 100 changes
             per day)

So, the first time you modify a file today, your serial number
in that file should be set to:


if you mod it again today, set it to 2000071102, and so on.

2. Run nslookup query without any hostname nor ip address to see if the
correct DNS server responds.

3. Check that a PTR record exists in the named.rev file or equivalent.

No doubt this one will come back to haunt me!


On Tue, 11 Jul 2000, at 14:42, Rae, Scott wrote:

> Hello,
> I'm having problems doing reverse lookups of two hosts that have
> recently been added to DNS database files. There are PTR records for the
> hosts in the named.rev file, and we can do reverse lookups for other
> The PTR records for the new hosts look good to me, though I must confess I
> have not done a lot of DNS things.
> I have followed the DNS troubleshooting guide in "NEtworking Unix"
> by Salim Douba, but I am still having problems. When I try the lookup I
> the "Non-existent host/domain" error, but of course the host and domain do
> exist.
> Does anyone have any ideas? I've run out of things to look at. One
> thing I don't fully understand is the serial numbers of the database
> Any help would be much appreciated.

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