Packet Tracer – Can Multiple Sites Be Hosted on the Same Web Server?

I've attempted many time to setup DNS doctoring but I just cant get it work, I believe because our ISR doesnt have the capability to peform the commands I'm trying

Your first problem is that you're using Cisco ASA commands on a Cisco router; you're also assuming this is a problem with your Cisco router.

In reality, this is a DNS issue that can be solved with your Cisco router; however, it's normally solved with a split-DNS

Is there another way to achieve DNS doctoring or otherwise access our local server using the external address?

Yes... Cisco calls it Network address translation (or nat)... Let's assume you have this topology...

                               +------------+
                        Fa0/0  | Cisco ISR  | Fa0/1
LAN w/ Webhost-----------------|            |-------------------
                        inside |            | outside (To ISP)
                   10.1.1.0/24 +------------+ 192.0.2.1
                                              192.0.2.2 (static translation for the webhost)

interface Fa0/0
 ip address 10.1.1.1 255.255.255.0
 no ip proxy-arp
 ip nat inside
interface Fa0/1
 ip address 192.0.2.1 255.255.255.0
 no ip proxy-arp
 ip nat outside
!
ip nat inside source list INSIDE_ADDRS interface FastEthernet0/1 overload
ip nat inside source static 10.1.1.50 192.0.2.2
!
ip access-list extended INSIDE_ADDRS
 permit ip 10.1.1.0 0.0.0.255 any
 deny   ip any any
!
ip route 0.0.0.0 0.0.0.0 192.0.2.254

Assume your internal Webhost address is 10.1.1.50 and you're using 192.0.2.2 (a second address given by your ISP) for your public A-record.. Thus, when you resolve "ourdomain.com" from google's resolver, you get...

[mpenning@Bucksnort ~]$ dig +short @8.8.8.8 ourdomain.com
10.1.1.50
[mpenning@Bucksnort ~]$

Assuming Bucksnort is 10.1.1.12, if you perform debug ip nat on your router during a DNS query, you see...

Sep 23 23:12:29.132 CDT: NAT: s=10.1.1.12->192.0.2.1, d=8.8.8.8 [0]
Sep 23 23:12:29.132 CDT: NAT: DNS resource record 192.0.2.2 -> 10.1.1.50
Sep 23 23:12:29.136 CDT: NAT: s=8.8.8.8, d=192.0.2.1->10.1.1.12 [628]
Sep 23 23:12:29.140 CDT: NAT: s=10.1.1.12->192.0.2.1, d=8.8.8.8 [0]
Sep 23 23:12:29.140 CDT: NAT: DNS resource record 192.0.2.2 -> 10.1.1.50
Sep 23 23:12:29.140 CDT: NAT: s=8.8.8.8, d=192.0.2.1->10.1.1.12 [629]
Sep 23 23:12:29.144 CDT: NAT: s=10.1.1.12->192.0.2.1, d=8.8.8.8 [0]
Sep 23 23:12:29.148 CDT: NAT: DNS resource record 192.0.2.2 -> 10.1.1.50
Sep 23 23:12:29.148 CDT: NAT: s=8.8.8.8, d=192.0.2.1->10.1.1.12 [630]

When companies merge, they often have this problem with overlapping addresses. Cisco has NAT Outside Source which helps to solve the problem. You can do an Internet search for "cisco ip nat outside source" to find information such as Sample Configuration Using the ip nat outside source list Command.

Introduction

This document provides a sample configuration with the ip nat outside source list command, and includes a brief description of what happens to the IP packet during the NAT process. You can use this command to translate the source address of the IP packets that travel from outside of the network to inside the network. This action translates the destination address of the IP packets that travel in the opposite direction—from inside to outside of the network. This command is useful in situations such as overlapping networks, where the inside network addresses overlap addresses that are outside the network. Let us consider the network diagram as an example.

Note: this should really only be a temporary situation, and you should strive to resolve the conflict. This is not something you want to maintain as a long term solution.

Another possible solution is to create VLANs on the switches just for the RANCID server connections, and you can set up different IP addresses for the switches on the server VLANs. This will not affect the switches and the existing LAN addressing, it just adds new addressing specifically for the server connections.