CNAMEs map nicknames to cannonical names. Fortunately they're not *that* agressive. :-) CNAMEs have very few uses (see above example, RFC 2317, ...). Be especially aware that nicknames must not be used as the right hand of NS, MX, ... RRs. Having CNAMEs in the RHS of an NS RR is not explicitly forbidden (yet?), so there's only an indirect way to explain why they are: they collide with glue RRs, leading to a violation of the rule that CNAMEs may not have any other RRs associated with them: XX. SOA () ns.foo.xx. A 1.2.3.4 foo.xx. NS ns.foo.xx. foo.xx. SOA () @ NS ns.foo.xx. ns.foo.xx. CNAME myhost.foo.xx. This leads to the illegal combination: ns.foo.xx. CNAME myhost.foo.xx. ns.foo.xx. A myhost.foo.xx. but not [visibly] in either of the zone files themselves! Piet