Comment 8 for bug 1634706

Also there are such messages in the log:
Error: Execution of '/bin/yum -d 0 -e 0 -y install cobbler' returned 1: Error downloading packages:
  cobbler-2.6.9-1.el7~mos11.noarch: [Errno 256] No more mirrors to try.
Error: /Stage[main]/Cobbler::Packages/Package[cobbler]/ensure: change from absent to present failed: Execution of '/bin/yum -d 0 -e 0 -y install cobbler' returned 1: Error downloading packages:
  cobbler-2.6.9-1.el7~mos11.noarch: [Errno 256] No more mirrors to try.

it seems like something was broken in your internet connection or firewall, as this package is fully downloadable from all the mirrors.