Configuring a DHCP Client
Most cards are recognized during the installation process, and the system is configured to use the correct kernel module for the card. If you install a card after installation, Kudzu should recognize it and prompt you to configure the corresponding kernel module for it. 
To configure a DHCP client manually, you need to modify the /etc/sysconfig/network-scripts/ifcfg-eth0 file to enable networking and the configuration file for each network device in the /etc/sysconfig/network-scripts directory. In this directory, each device should have a configuration file named ifcfg-eth0 where eth0 is the Lan network device name.

The /ifcfg-eth0 file should contain the following line:

NETWORKING=yes

You might have more information in this file, but the NETWORKING variable must be set to yes if you want networking to start at boot time.

The /etc/sysconfig/network-scripts/ifcfg-eth0 file should contain the following lines:

DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes

You need a configuration file for each device that you want to configure to use DHCP.

If you prefer a graphical interface for configuring a DHCP client, use neat.