I have a 1811 using NAT to get our internal services out to the
internet. I have 2 dns servers on the inside of our network that serve
public queries.
I have a class c (provided by my ISP) for my outside interface. I have
the last 11 addresses setup in a pool to allow my workstations to surf
the net. I have setup static (one to one) mappings for several
services inside (e-mail, www, DNS).
My DNS servers are on different class-c networks inside.
-Secondary DNS xxx.xxx.216.107
/
- classC1 xxx.xxx.216.0
/
Internet --1811
\
- classC2 xxx.xxx.217.0
\
-Primary
DNS xxx.xxx.217.183
On classC1, I have an external address natted to xxx.xxx.216.107
(secondary DNS)
On classC2 I have an external address natted to xxx.xxx.217.183
(primary DNS)
As long as I have the nat statement on classC1 working, DNS works
properly. If I remove the classC1 staic nat, I can no longer reach the
primary DNS server. If I try and create an extended NAT translation,
it fails. I can not reach the primary or secondary server.
If I run debugs on the NAT, I can see that incoming DNS queries are
going to xxx.xxx.217.183.
I've attached a copy of my config (less the un-interesting bits).
