When el6 won’t apply a default route

I was doing some network reconfiguration on a box recently. I was switching from a static IP setup (which was originally configured during install) to a DHCP setup.

Problem was, regardless of what I did, I could not get the default route from the DHCP server to apply. I end up with no default route after getting an address.

A lot of googling, mailing list asking, and IRC later, I finally discovered that the file /etc/sysconfig/network had this line in it:

GATEWAY=<some ip address>

It must have been put there during the original install.

Removing that and restarting networking caused the machine to properly apply the default route give to it by the DHCP server.