The domain controller that currently hosts the infrastructure master role for this domain also is a global catalog server. ...

The domain controller that currently hosts the infrastructure master role for this domain also is a global catalog server. In a multidomain environment, hosting the infrastructure master role on a global catalog server can cause problems (unless all other domain controllers in the domain are also global catalog servers). You can either transfer the infrastructure master role to this domain controller now by setting the 'TransferIMRoleIfNecessary' option to 'YES' to prevent these problems or you can correct the configuration later, either by transferring the infrastructure master role to another domain controller later, or by ensuring that all domain controllers for this domain are also global catalog servers.