Gateway is set in the /etc/sysconfig/network file.
GATEWAY=192.168.0.2

IP Address is set in the "/etc/sysconfig/network-scripts/if-eth0" file.
DEVICE="eth0"
IPADDR="192.168.0.2"
NETMASK="255.255.0.0"
ONBOOT="yes"

DNS is set in the "/etc/resolv.conf"
domain somewhere.com
search somewhere.com
nameserver 192.168.0.1