After configuration, DNS starts automatically if
/etc/named.boot is present. When named starts up, it
writes its process id to the file /etc/named.pid. This is useful
to programs that want to send signals to named.
If you encounter problems with named, first view the logfile
/usr/adm/syslog for any errors. If none are found, send one or
more signals with the kill command to named
to troubleshoot DNS without restarting
the named process. The signals are:
SIGHUP (kill -1)
Causes named to read named.boot and reload the database,
overwriting cached data. This is useful when you make
a change to a data file and you want named's internal database
to reflect the change.
SIGHUP also has the effect of scheduling all secondary zones
for serial-number checks, which could lead to zone transfers ahead of
the usual schedule. Normally, serial-number comparisons are done only at
the intervals specified in the zone's SOA record.
SIGINT (kill -2)
Dumps the current database and cache to /usr/tmp/named_dump.db.
This gives you an indication to whether the database was loaded
correctly.
SIGUSR1 (kill -16)
Turns on debugging. Each following USR1 increments the debug level.
The output goes to /usr/tmp/named.run.
SIGUSR2 (kill -17)
Turns off debugging completely.
SIGWINCH (kill -20)
Toggles tracing of all incoming queries. The trace is sent
to /usr/adm/syslog and provides a large amount of data.