Cisco Router as a DNS server

Not exactly like a DNS server that is hosted from a server and so on and so forth, the Cisco Router can act like a DNS server without the service stated above. It can even act as a proxy dns server, meaning forwarding the request to the upstream DNS server and cache the replies from the DNS server, so it can use the cache entries for other requesting hosts. We will only focus on the simple and practical configuration. I don't even know if this feature can be called a "DNS server" feature. :P If you have your own Dynamips Lab and has fixed ip addresses, it would be easier though to use hostnames when trying to ping devices. This can be achieved by the "ip host" command. It can be configured as the example below.

Router(config)#ip host R1 1.1.1.1
Router(config)#ip host R2 2.2.2.2
Router(config)#ip host R3 3.3.3.3
Router(config)#ip host R4 4.4.4.4

Let's do a ping test.

Router#ping R1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
...

Well, R1 now resolves to 1.1.1.1. There you have it, makes life easier! :P