Once you have installed CentOS server or have created VPS, configure static IP address for connect an individual network. The most common interface file is ifcfg-eth0. As an administrator can manage the interface function in the server.

The below configuration can fix static IP address.

Open the ifcfg-eth0 file and add below configure lines,

#  vi /etc/sysconfig/network-scripts/ifcfg-eth0

TYPE=Ethernet
DEVICE=eth0
HWADDR=00:25:90:57:7A:8B
IPADDR=192.168.0.10
NETMASK=255.255.255.240
BROADCAST=192.168.0.200
ONBOOT=yes
GATEWAY=192.168.0.105

IPADDR  : your server IP Address is : 192.168.0.10

ONBOOT :
If have set  ONBOOT=Yes device should be activated at boot-time.
If have set  ONBOOT=No  device should not be activated at boot-time.

GATEWAY :  IP address of the network router.

HWADDR  : the hardware address of the Ethernet device.

Restart your network sercices,
 
# /etc/init.d/network restart

Configure DNS Server:
 
# vi /etc/resolv.conf

nameserver 127.0.0.1
nameserver 192.168.0.101
nameserver 192.168.0.102

If you need to check NetMask, Gateway, IP Address and Network interface.
 
# route -n

Kernel IP routing table
Destination         Gateway           Genmask               Flags    Metric Ref    Use Iface
192.168.0.192     0.0.0.0              255.255.255.240     U            0      0        0 eth0
169.254.0.0        0.0.0.0               255.255.0.0             U          1002   0        0 eth0
0.0.0.0              192.168.0.105      0.0.0.0                  UG            0      0        0 eth0