In article <b7e7d7da6cad1c28909a241714fb3a89@xxxxxxxxxxxxxxxxxxx> you write: >Section 2 says: > > o The system MUST be able to run an authoritative server on one of > the IPv4 loopback addresses (that is, an address in the range > 127/8). > >Why is there a requirement for an *IPv4* loopback address? Is there any >problem with running on the IPv6 loopback address? There's only one v6 loopback address, and it often has a local DNS cache listening. R's, John