Installing and Administering Internet Services

150 Chapter3
Configuring and Administering the BIND Name Service
Troubleshooting the BIND Name Server
dump, starting with unknown query types.
iqueries is the number of inverse queries. Inverse queries can be used
to map a host address to a domain name, although PTR queries
(discussed below) are the normal method. Some versions of nslookup
send inverse queries when they are starting up.
duplicate queries are retransmitted queries for pending lookups that
the resolver sends to the name server. The name server detects the
duplicate queries and discards them.
responses is the number of response packets that the name server
receives from queries to other name servers.
duplicate responses are response packets from remote name servers
for queries that are no longer pending. The name server retransmits
queries to remote name servers. If the remote server responds to the
original query and responds to the retransmitted query, the local name
server discards the second response as a duplicate.
OK answers is the number of responses to queries that contain some
information.
FAIL answers is the number of responses indicating either that the
name does not exist or that there is no data of the requested type for this
name.
FORMERR answers is the number of malformed response packets from
other name servers. A message is sent to the syslog daemon listing the
sender of the malformed response packet.
system queries are queries generated by the name server. These
usually occur when the name server detects another name server listed
for a domain for which there is no address data. The system query is an
attempt to find the address data for that name server. System queries
are also used to keep up-to-date information about the name servers for
the root domain.
prime cache calls are calls to update the information about the name
servers for the root domain.
check_ns calls are calls to check the state of the information about the
name servers for the root domain.
bad responses dropped are responses from remote name servers that
are dropped. These occur most often when the remote name server
responds with SERVFAIL, indicating a problem with the server’s domain
data.