We use the Incero Mirror, because well it is very fast as we are part of the Incero network
http://mirror.incero.com/
So when doing a net install, you would use paths as such when you pick to install from URL.
Cent OS 6.5 32-BIT (Latest)
http://mirror.incero.com/centos/6.5/os/i386/
Cent OS 6.5 64-BIT (Latest)
http://mirror.incero.com/centos/6.5/os/x86_64/
Cent OS 6.4 32-BIT
http://mirror.incero.com/centos/6.4/os/i386/
Cent OS 6.4 64-BIT
http://mirror.incero.com/centos/6.4/os/x86_64/