Assuming you are using eth0
Note this will work for any version of CentOS and basically any version of Redhat Linux or Redhat based distribution.
You would need to create a new file
[code:1:02f8d34c30] /etc/sysconfig/network-scripts/ifcfg-eth0:0[/code:1:02f8d34c30]
DEVICE=eth0:0
the ":0" at the end specifies alias 0 we could actually change this to ":99" or ":blabla" and it will still work.
The rest should be straight forward as long as you know how to set a static IP in general.
Edit your new file:
[code:1:02f8d34c30]/etc/sysconfig/network-scripts/ifcfg-eth0:0[/code:1:02f8d34c30]
And it should look like this:
[code:1:02f8d34c30]DEVICE=eth0:0
BOOTPROTO=static
IPADDR=ip.ip.ip.ip
NETMASK=255.255.255.0
GATEWAY=ip.ip.ip.ip
ONBOOT=yes[/code:1:02f8d34c30]
One more thing, to apply the changes and make them active and test what happens after a reboot
type [code:1:14b16772c8]"service network restart"[/code:1:14b16772c8]
One more thing, it can be a great thing to have a combination of a "DHCP" dynamic IP address and setting a static one.
This sort of guarantees network connectivity, say eth0 doesn't get an IP lease from the DHCP server then your server is basically down.
But if your eth0:0 alias is set statically then you can connect through the static IP address.
It just makes good sense!