Activate NIC or network card at boot time for Redhat/CentOS

In recent RHEL6/CentOS6 NIC is not getting up by default. So once you login we have to up the network interface to make it work properly. To make the interface available at the time of boot we have to set ONBOOT option in ifcfg-eth0 file.

Open the file In file /etc/sysconfig/network-scripts/devices/ifcfg-eth0 and change ONBOOT value to yes

Before editing the file.

DEVICE=eth0
HWADDR=52:54:00:60:af:6d
NM_CONTROLLED=yes
ONBOOT=no
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no

After editing the file

DEVICE=eth0
HWADDR=52:54:00:60:af:6d
NM_CONTROLLED=yes
ONBOOT=yes
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no

Reboot the machine and your NIC interface will be activated at the time of booting.