Some time we are unable to find network information on ifcfg command or network connection does not work after cloning.
To see all interfaces ifcfg -a
To force CentOS 6 to re-detect network interfaces
Delete the MAC Address from ifcfg-eth0 file
vi /etc/sysconfig/network-scripts/ifcfg-eth0
Remove the old 70-persistnet-net.rules file with the following command
rm -f /etc/udev/rules.d/70-persistent-net.rules
Reboot the machine.
I got quick reference from link