Quick and Dirty RHEL/CentOS Network Configuration

/etc/resolv.conf:
nameserver #.#.#.#
nameserver #.#.#.#

Naturally, replace #.#.#.# with the IP addresses of your nameservers.

/etc/sysconfig/network:
NETWORKING=yes
HOSTNAME=BOX
DOMAIN=DOMAIN.FOO

HOSTNAME is, of course, where you put the hostname of your box. This should not be a FQDN; the domain should end up in the DOMAIN variable.

/etc/sysconfig/network-scripts/ifcfg-eth0:
DEVICE=eth0
BOOTPROTO=static
IPADDR=172.16.42.142
NETMASK=255.255.255.0
NETWORK=172.16.42.0
BROADCAST=172.16.42.255
GATEWAY=172.16.42.1
ONBOOT=yes

This assumes the IP of your box is 172.16.42.142 with a netmask of 255.255.255.0. Network and broadcast will be set up in the same fashion, using .0 at the end of network and .255 for broadcast. Gateway may fluctuate depending on your own network setup – usually, gateways are located at .1, but your mileage may vary.

/etc/init.d/networking restart

…And yer off.