CentOS 6 - Set Static IP

In order to set static ip on CentOS 6:

1. Open ifcfg-Auto_eth0 file at /etc/sysconfig/network-scripts folder
1. sudo vi /etc/sysconfig/network-scripts/ifcfg-Auto_eth0
1. The file name could be different. It could be ifcfg_eth0, too.
2. Change the content to something like below:
1. TYPE=Ethernet
   BOOTPROTO=none
   IPADDR=192.168.11.30
   PREFIX=24
   GATEWAY=192.168.11.1
   DNS1=192.168.11.10
   DNS2=209.18.47.62
   DEFROUTE=yes
   IPV4_FAILURE_FATAL=yes
   IPV6INIT=no
   NAME=eth0
   UUID=06823066-d18a-4af3-b3a0-e2158d152465
   ONBOOT=yes
   HWADDR=00:0C:29:D3:6C:5C
   LAST_CONNECT=1523339343
3. :wq
4. Open resolv.conf and check or correct the nameserver
1. sudo vi /etc/resolv.conf
2. It should be like the following.
1. nameserver 192.168.11.10
2. nameserver 209.18.47.62
5. Restart network
1. sudo /etc/init.d/network restart

Other admins use /etc/sysconfig/network file to specify the default gateway. They may not specify DNS1 or DNS2 in ifcfg-eth0 or ifcfg-Auto_eth0 file. Instead, only the /etc/sysconfig/network file is used to specify the nameservers. 

Below is another example of setting up static ip on CentOS 6

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

DEVICE="eth0"
NM_CONTROLLED="yes"
ONBOOT=yes
HWADDR=A4:BA:CC:37:F1:03
TYPE=Ethernet
BOOTPROTO=static
NAME="System eth0"
UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03
IPADDR=192.168.11.30
NETMASK=255.255.255.0


## Configure Default Gateway
#
# vi /etc/sysconfig/network

NETWORKING=yes
HOSTNAME=centos6
GATEWAY=192.168.11.1


## Restart Network Interface
#

/etc/init.d/network restart

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

nameserver 192.168.11.10      # Replace with your nameserver ip
nameserver 209.18.47.62       # Replace with your nameserver ip