This is a common problem also when a Vmware machine is moved to another server.
It is beacause the new card has a different MAC address.
Unlike Ubuntu Desktop, the server version is desgned NOT to make an assumption of how the card is configured – just in case it gets it wrong & places vulnerable data outside a firewall on the Internet.
You can enable the card easliy by deleting a file:
sudo rm /etc/udev/rules.d/70-persistent-net.rules
Then reboot.
This file is recreated with the new card MAC address upon reboot.
Then check your settings.
EDIT****
This also applies to CentOS 6.x
