In the past (Blasco has mentioned this before) we said to include the zone-c of the parent zone, since he/she maintains the MX records. Sounds reasonable! Not at all: by the same token one could argue that the person maintaining a top level zone file should be registered as the zone-c for every primary subdomain, since (s)he maintains the NS records [in the top level zone file], just like in the case of MX-only domains (s)he maintains the MX records [in the top level zone file]. I've always just copied the admin-c into the zone-c in these cases, for the simple reason that there is no such thing as a zone for an MX-only domain and the admin contact can be held equally well responsible for the MX records, even though (s)he doesn't put/maintain them in the next higher zone file, as is the case with NS records. I would suggest to consider the presence of the *zc attribute mandatory only if *ns attributes are present in the domain entry. Piet