How To Configure DHCP On A Cisco Router - Computers - Certification

DHCP is used quite often every single day in small and large network environment. So much of what it does is behind the scenes that even though it works and our computers still continue to work and go out onto the internet we kind of forget that DHCP is one of the contributing protocols that make everything run smooth.

As a network administrator you should be familiar with how to set up a DHCP server so that you can ensure that each computer automatically receive an ip address, knows how to get out the default gateway, and resolve domain names. DHCP stands for Dynamic Host Configuration Protocol and it is in charge of making sure all of this happens pretty much in the background with anyone knowing. This is, if it all works okay.

The cool thing about Cisco routers is that they can also be configured as a DHCP server so that you do not need to have some other dedicated server to add to your already crowded server room.

When you configure your Cisco router as a DHCP Server you will need to decide on a name for the "pool" of ip addresses that will be used for assigning out to hosts. Some of the optional setting that you can use to assign out include dns servers, domain name, lease time, and net-bios name. Here are the commands to follow:

Basic Configuration:router(config)# ip dhcp pool NAMErouter(dhcp-config)# network 192.168.1.0 255.255.255.0router(dhcp-config)# default-router 192.168.1.1

Optional Commands:router(dhcp-config)# dns-server 4.4.4.4 8.8.4.4router(dhcp-config)# domain-name name.comrouter(dhcp-config)# lease infinite

Excluded IP Addresses:router(config)# ip dhcp excluded-address 192.168.1.1 192.168.1.10

Turn DHCP Server ON:router(config)#service dhcp

Now that you have your DHCP Server configured you can start using it. Computers that are joining the network will automatically receive on ip address starting with 192.168.1.11 and going all the way up to 192.168.1.254. The 10 ip addresses that we excluded are for other servers in the network that need to have a static ip address or one the doesn't change.

Make sure that any static ip addresses that have already been assigned do not fall outside of the excluded address range. If not it is quite possible that their could be duplicate ip addresses which can cause some weird network errors.

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