On Fri, 17 Dec 2004 17:52:24 -0500, Jesse Guardiani <jesse at wingnet dot net> wrote:
> Hello,
> 
> 192.168.1.1/24 is my LAN at work.
> 192.168.88.1/24 is my LAN at home.
> 
> The two are connected together by a m0n0wall -> m0n0wall
> IPSec VPN. The m0n0wall at work runs 1.11 and the
> m0n0wall at home runs 1.2b3.
> 
> In the interest of having my office network
> m0n0wall's internal DNS available to my LAN
> at home, I have attempted to set my m0n0wall at
> home's DNS server to 192.168.1.1 in:
>     System -> General Setup -> DNS Servers
> 
> In addition, as both locations connect to the
> internet via PPPoE over ADSL, I have unchecked
> the option:
>     "Allow DNS server list to be overridden by DHCP/PPP on WAN"
> On the same page.
> 
> I rebooted the home m0n0wall (the only one with
> DNS changes), and a `cat /etc/resolv.conf` from
> exec.php is showing "192.168.1.1" as the only
> nameserver, but general DNS queries fail.
> 
> However, I *can* perform `dig` operations from my linux
> machine at home, over the IPSec link, to the m0n0wall
> at work, as illustrated below:
> 

Same reason you can't query SNMP over VPN, and same fix.  
http://m0n0.ch/wall/docbook/faq-snmpovervpn.html

-Chris