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NAT & 2600 Router

The setup :- One Serial Interface out to an ISP who maintain the DNS Servers

Two Ethernet interfaces 0/0 & 0/1 into the corporate network.

Interface e0/0 connects all the users together and e0/1 is the DMZ which contains web servers.

NAT is applied to the Serial interface and the E0/1 interface.

The problem :- When users on e0/0 want to connect to a web site that is on a web server in the DMZ (e0/1)and they request it by domain name (ie http://www.fred.com) the user gets the Cannot find server error but if they request the site by it's internal IP (192.x.x.x) then they can get the requested page.

However if they request an external web page ie Cisco.com they get through straight away.

On a PIX firewall there is a Alias command which solves this problem but is there a way via NAT and how can this be resolved???

1 REPLY
Cisco Employee

Re: NAT & 2600 Router

the problem is that you dns server is on the outside.

So, when a user on the inside request a name translation from the dns server, it gets the outside address of your server (not the inside address).

Therefore traffic is sent out to the outside instead of the DMZ.

A solution is to have a dns on the inside.

Another solution is to use overlapping config as described in the following doc :

http://www.cisco.com/warp/public/556/3.html

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