# wget http://ftp-stud.fht-esslingen.de/pub/Mirrors/centos/6/os/x86_64/Packages/centos-release-6-5.el6.centos.11.1.x86_64.rpm
# yum shell
Setting up Yum Shell
> remove redhat-release
Setting up Remove Process
> install centos-release-6-5.el6.centos.11.1.x86_64.rpm
> run
===============================================================================================================================================================================
Package                                  Arch                      Version                                Repository                                                     Size
===============================================================================================================================================================================
Installing:
centos-release                           x86_64                    6-5.el6.centos.11.1                    /centos-release-6-5.el6.centos.11.1.x86_64                     32 k
Removing:
redhat-release-server                    x86_64                    6Server-6.5.0.1.el6                    @rhel-x86_64-server-6                                         119 k

Transaction Summary
===============================================================================================================================================================================
Install       1 Package(s)
Remove        1 Package(s)

Total size: 32 k
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : centos-release-6-5.el6.centos.11.1.x86_64                                                                                                                   1/2
  Erasing    : redhat-release-server-6Server-6.5.0.1.el6.x86_64                                                                                                            2/2
  Verifying  : centos-release-6-5.el6.centos.11.1.x86_64                                                                                                                   1/2
  Verifying  : redhat-release-server-6Server-6.5.0.1.el6.x86_64                                                                                                            2/2

Removed:
  redhat-release-server.x86_64 0:6Server-6.5.0.1.el6                                                                                                                          

Installed:
  centos-release.x86_64 0:6-5.el6.centos.11.1                                                                                                                                 

Finished Transaction
> Leaving Shell

# cat /etc/redhat-release
CentOS release 6.5 (Final)

# yum remove rhn\*
...

# yum update
...