I was recently working on a server where a user on the server was concerned with these log messages:
Oct 7 20:59:33 web named[13698]: client 111.222.333.444#50389: updating zone 'domain.com/IN': update failed: 'RRset exists (value dependent)' prerequisite not satisfied (NXRRSET)
Oct 7 20:59:34 web named[13698]: client 111.222.333.444#50392: update 'domain.com/IN' denied
Oct 7 21:59:35 web named[13698]: client 111.222.333.444#50422: updating zone 'domain.com/IN': update failed: 'RRset exists (value dependent)' prerequisite not satisfied (NXRRSET)
Oct 7 21:59:35 web named[13698]: client 111.222.333.444#50425: update 'domain.com/IN' denied
Oct 7 22:59:20 web named[13698]: client 111.222.333.444#50458: updating zone 'domain.com/IN': update failed: 'RRset exists (value dependent)' prerequisite not satisfied (NXRRSET)
The messages here are actually showing that named is doing its job well. Some user was attempting to dynamically update a DNS zone repeatedly, but named was rejecting the updates since they were not coming from a valid sources.
Further reading:
Zytrax.com: DNS BIND Zone Transfers and Updates
Internet Systems Consortium: Dynamic Updates
