dhcpd sends 127.0.1.1 as DNS server

On Tue, Mar 10, 2009 at 09:01:48AM -0000, Patrick Ben Koetter wrote:
> Ubuntu configures sets the hostname in /etc/hosts and assigns it to
> 127.0.1.1:
>
> 127.0.0.1 localhost
> 127.0.1.1 server.example.com server
>
> The dhcpd server picks this up and sends it as primary DNS server (DHCP and DNS are on the same machine here) to dhcp clients (see attached dhcpdump output).
> Assigning the wrong DNS server leads to timeouts on Mac and Linux (Unix) clients, but it does not seem to affect Windows systems.
>

Could you post /etc/dhcpd.conf and /etc/resolv.conf from the system
running the dhcpd server?

  status incomplete

--
Mathias Gug
Ubuntu Developer http://www.ubuntu.com

I have seen this as well.

In my case what is happening is this:

1) I have one interface which is dynamically assigned via DHCP (upstream to my ISP)
2) I have a second interface which is statically assigned (my local LAN interface).
3) I have a local name server (for caching and for local name resolution).
4) I have /etc/network/interfaces configured to statically assign the local interface, and to set the name server for the local interface to 127.0.0.1, so that when %#@()&*$ network manager OVERWRITES THE /etc/resolv.conf file I SET UP it will at least overwrite it correctly for the local machine.
5) HOWEVER, the same entity that is overwriting /etc/resolv.conf is also overwriting /etc/dhcp3/dhcpd.conf and setting the nameserver to 127.0.0.1, which is then served out to the network clients.

FIRST OF ALL: There should be a way I can tell the network manager scripts "I have configured these files - LEAVE THEM THE HELL ALONE!"

Second of all, the scripts should be "smart" enough to detect a nameserver of 127.0.0.1 and NOT set DHCPD to do that.

Is this not the explanation for the 127.0.1.1 nameserver?

https://wiki.ubuntu.com/QuantalQuetzal/ReleaseNotes/UbuntuDesktop#QuantalQuetzal.2BAC8-ReleaseNotes.2BAC8-CommonInfrastructure-1.Networking

BR
Pierre