Simple DNS split example

[Marcio Souza]

Hello,

I'm using a Cisco 1841 over DSL for internet access and a personal web server. I have searched for a simple DNS split configuration onet the Internet, but none of the examples I have found had worked on my router.

Does anyone have a simple example of DNS split to share with me? I'm newbie on Cisco routers.

Regards,

Marcio 

[Vasilii Mikhailovskii]

Hello, Marcio.

It's not recommended to make your Cisco a dns, server, but it's possible:

ip name-server 8.8.8.8
ip domain-lookup
ip host <my_WEBserver_URI> 192.168.0.99
ip dns server

And make your router a preferred DNS on your computer/laptop.

PS: ASA has DNS doctoring feature, but it's not your case (to have ASA) :)

[Peter Paluch]

Hi Marcio,

There is currently an Ask the Expert session running at this page which is focused exactly on DNS and DHCP and issues like yours. You may want to repost this thread there.

In any case, what IOS version is running on your 1841 router? In addition, can you post the split DNS configuration you have tried to implement? Please be aware of the fact that split DNS has been added around version 12.4(9)T so if you happen to run an older IOS, it perhaps does not support the split DNS yet.

Best regards,
Peter

[Marcio Souza]

Hello Peter!

I'm not using the Split DNS on my router yet! Let me explain what's happening.

I have a web server running on my private network on the machine 10.10.10.11 and I can access it using the mentioned address. This server have a FDQN and I can reach it from outside my network (Internet) without any issue.

I would like to use the FDQN to access it from machines inside my private network, but I cannot due to some security feature on cisco router. I have read some articles stating we need to have a "Split DNS" to allow machines inside the private network can access the web server on the address 10.10.10.11 using the FDQN, as machines outside the private network do.

I tryed to find a simple "Split DNS" to try here, but I didn't found any that could be used. All I have found are very complex examples. I'm using the following firmaware on the router:

HomeNet#sh version
Cisco IOS Software, 1841 Software (C1841-IPBASEK9-M), Version 12.4(24)T3, RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2010 by Cisco Systems, Inc.
Compiled Tue 23-Mar-10 05:11 by prod_rel_team

ROM: System Bootstrap, Version 12.4(13r)T5, RELEASE SOFTWARE (fc1)

HomeNet uptime is 23 hours, 37 minutes
System returned to ROM by power-on
System image file is "flash:c1841-ipbasek9-mz.124-24.T3.bin"

I'm not using Cisco Router as a DHCP server, since I have a Linux machine running ISC-DHCP-SERVER on my network. I have attached some pictures to ilustrate the issue, one accessing using FDQN and other using server IP address.

Best Regards!

Marcio