dhcp not updating dns server

[Glenn Satchell]

>From: James Dinkel <jdinkel at gmail.com>
>Date: Mon, 14 Dec 2009 17:22:58 -0600
>Subject: Re: dhcp not updating dns server
>To: dhcp-users at lists.isc.org
>
> Well I tried this on Ubuntu Hardy and at least now I'm getting something
> showing up in tcpdump:
> 
> 17:12:27.079892 IP 192.168.101.254.60433 > 192.168.100.2.53: 46870+ PTR?
> 5.50.168.192.in-addr.arpa. (43)
> 17:12:27.082444 IP 192.168.100.2.53 > 192.168.101.254.60433: 46870 NXDomain*
> 0/1/0 (133)

Sorry to disappoint you, but the first packet is a query for the
hostname corresponding to 192.168.50.2, and the second is a reply "no
such address".

> 17:15:43.605453 IP 192.168.100.2.138 > 192.168.101.255.138: NBT UDP
> PACKET(138)

This is a netbios packet, probably a lookup for a samba share, or a
windows PC doing its normal thing.

> 
> It's virtuall the same configuration.  Here is my config file:
> -------------------------------------------------
> ddns-update-style interim;
> ignore client-updates;
> zone COMPANY.COM. {
>     primary 192.168.100.2;
> }
> zone 100.168.192.in-addr.arpa. {
>     primary 192.168.100.2;
> }
> 
> 
> # option definitions common to all supported networks...
> option domain-name "company.com";
> option domain-name-servers 192.168.100.2, 192.168.100.3;
> 
> default-lease-time 6000;
> max-lease-time 7200;
> 
> # If this DHCP server is the official DHCP server for the local
> # network, the authoritative directive should be uncommented.
> authoritative;
> 
> # This is a very basic subnet declaration.
> 
> subnet 192.168.100.0 netmask 255.255.254.0 {
>   range 192.168.100.100 192.168.100.200;
>   option routers 192.168.100.1;
> }
> -------------------------------------------------
> 
> I just edited the default dhcpd.conf file in Ubuntu.  It looks identical
> except there is an "authoritive" directive in this one.  I have not tried it
> with that "authoritative" commented out.  The updates are still not showing
> up on the dns server and I would prefer to do this on Red Hat but at least
> I'm getting something in the tcpdump output.
> 
> James

What records are in syslog on the dhcpd server? Does it show dhcpd
sending out dhcp requests/replies to the clients? There are other clues
there too, as to whether the PC is replying with a hostname. What OS is
on the clients?

regards,
-glenn