CentOS 7 GDM forces you to create a local account even when using LDAP, NIS, etc

This is a super annoying issue.  Here is how I got around it.

After install switch to tty2 Ctrl+Alt+F2.  Login as root.  Setup your choice of authentication..

Before logging out change this setting.

Edit /etc/gdm/custom.conf

Look for the section that says [daemon]  and add the following:

InitialSetupEnable=false

Save and exit.  Reboot the machine and login.

 Source:  Link