Command Center

Q. How do I setup my Red Hat / CentOS / Fedora Linux system to get IP address and other information via a DHCP server for eth0 interface?

A. You can edit eth0 configuration file to switch between static and dhcp networking configuration under RHEL / Fedora or CentOS Linux. Simply edit /etc/sysconfig/network-scripts/ifcfg-eth0 file.
Backup existing static configuration

First backup existing network configuration file using cp command:
# cp /etc/sysconfig/network-scripts/ifcfg-eth0 /root/ifcfg-eth0.bak
Configuring a DHCP Client

Setting up a Linux for dhcp can be done by editing file using a text editor such as vi:
# vi /etc/sysconfig/network-scripts/ifcfg-eth0
Following is sample static configuration:
DEVICE=eth0
BOOTPROTO=static
HWADDR=00:19:D1:2A:BA:A8
IPADDR=10.10.29.66
NETMASK=255.255.255.192
ONBOOT=yes
Replace static configuration with DHCP:
DEVICE=eth0
BOOTPROTO=dhcp
HWADDR=00:19:D1:2A:BA:A8
ONBOOT=yes
Save and close the file. Just restart network service:
# /etc/init.d/network restart
Please note that you need a configuration file for each device that you want to configure to use DHCP.

Reference: http://www.cyberciti.biz/faq/setting-up-a-linux-for-dhcp/