Cobbler is packaged for RHEL variants through the Fedora EPEL (Extra Packages for Enterprise Linux) system. Follow the directions there to install the correct repo RPM for your RHEL version and architecture. For example, on for a RHEL6.x x86_64 system:
Be sure to use the most recent X.Y version of the epel-release package.
Once that is complete, simply use the yum command to install the cobbler package:
As noted above, new releases in the Fedora packaging system are held in a "testing" repository for a period of time to vet bugs. If you would like to install the most up to date version of cobbler through EPEL (which may not be fully vetted for a production environment), enable the -testing repo when installing or updating:
$ sudo yum update --enablerepo=epel-testing cobbler
Once cobbler is installed, start and enable the service:
And (re)start/enable Apache: