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This appendix provides detailed information about named syntax
and the commands and files used to configure it. This is primarily
a reference to use in conjunction with the tutorial information in
Chapter 8, Configuring DNS Name Service . This information is useful to any domain administrator. The server side of DNS is run by the name server daemon, named.
The syntax of the named command is:
[1] named [-d level] [-p port[/localport]] [[-b] bootfile] [[-q] [[-r] The three options used on the named command line are: - -d
level Logs debugging information in the file /usr/tmp/named.run. The
argument level is a number from 1 to 9. A higher level
number increases the detail of the information logged, but even when
level is set to 1, the named.run file grows very
rapidly. Whenever you use debugging, keep an eye on the size of the
named.run file and use SIGUSR2 to close and remove the file if
it gets too large. Signal handling is covered in the next section. It is not necessary to turn on debugging with the -d option to
receive error messages from named. named displays error
messages on the console and stores them in the messages, even if
debugging is not specified. The -d option provides
additional debugging information. - -p
port[/localport] Defines the UDP/TCP port used by named. port is the port
number used to connect to the remote name server. localport is
the number of the port on which the local name server daemon listens
for connections. If the -p option is not specified, the
standard port (53) is used. Since port 53 is a well-known port,
changing the port number makes the name server inaccessible to
standard software packages. Therefore, -p is only used for
testing. - -b
bootfile Specifies the file named uses as its configuration
file. By default the configuration file is /etc/named.boot, but
the -b option allows the administrator to choose another
configuration file. Note that the -b is
optional. As long as the filename used for bootfile doesn't
start with a dash, the -b flag is not required. Any filename
written on the named command line is assumed to be the boot
file. - -q
Logs all incoming queries. named must be compiled
with the QRYLOG option set to enable this type of logging. - -r
Turns off recursion. With this option set, the server will
only provide answers for zones for which it is an authoritative server.
It will not pursue the query through other servers or zones.
named handles the following signals: - SIGHUP
Causes named to reread the named.boot file and reload the
name server database. named then continues to run with the new
configuration. This signal is particularly useful for forcing
secondary servers to reload a database from the primary
server. Normally the databases are downloaded from the primary server
on a periodic basis. Using SIGHUP causes the reload to occur
immediately. - SIGINT
Causes named to dump its cache to
/usr/tmp/named_dump.db. The dump file contains all of the domain
information that the local name server knows. The file begins with the
root servers, and marks off every domain under the root that the local
server knows anything about. If you examine this file, you'll see that
it shows a complete picture of the information the server has learned. - SIGUSR1
Turns on debugging; each subsequent SIGUSR1 signal increases the level
of debugging. Debugging information is written to
/usr/tmp/named.run just as it is when the -d option is
used on the named command line. Debugging does not have to be
enabled with the -d option for the SIGUSR1 signal to
work. SIGUSR1 allows debugging to be turned on when a problem is
suspected, without stopping named and restarting it with the
-d option. - SIGUSR2
Turns off debugging and closes /usr/tmp/named.run. After issuing
SIGUSR2, you can examine named.run or remove it if it is getting
too large.
Optionally, some other signals can be handled by named.
These additional signals require named to be compiled with the
appropriate options to support the signals: - SIGABRT
Writes statistics data to /var/tmp/named.stats. named
must be compiled with -DSTATS for this signal to work. - SIGSYS
Writes profiling data into the /var/tmp directory.
named must be compiled with profiling to support this signal. - SIGTERM
Writes back the primary and secondary database files. This is used to
save data modified by dynamic updates before the system is shut
down. named must be compiled with dynamic updating enabled. - SIGWINCH
Toggles logging of all incoming queries via syslogd. named
must be compiled with QRYLOG option to support this.
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