If you find yourself (Like I did at 2 AM on Easter Sunday) with a down cPanel server on Linode, the problem is likely due to a networking issue. The fix is pretty simple.
echo "NETWORKING=yes" >> /etc/sysconfig/network
echo "GATEWAY=x.x.x.x" >> /etc/sysconfig/network
If you need to find your gateway IP that can be found with this command:
grep GATEWAY= /etc/sysconfig/network-scripts/ifcfg-eth0
Then just reboot the server.