GC subfolder under _msdcs in child domain missing

In our DNS Manager console, we are told that the gc and domains subfolders are supposed to be under _msdcs in the child domain (ct.er.lcl).We do have these subfolders under _msdcs in the forest root domain (er.lcl).

Is that true ? If so, how can we get these subfolders under the _msdcs in the child domain? We have a 2008 Active-Directory Integrated zone. Zone replication scope is Replicate to all DNS servers in this forest.

Thanks,

Charlie