Appendix C. A named Reference
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". This
information is useful to any domain administrator.
C.1. The named Command
The server side of DNS is run by the name server daemon,
named. The syntax of the named
named [-d level] [-p port] [[-b|c] configfile] [-q -r -f -v] [-u username]
[-g groupname] [-t path] [-w path] [configfile]
The options used on the named command
- -d level
Logs debugging information in the file
named.run. The argument
level is a number from 1 to 11. 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 ndc
notrace or SIGUSR2 to close 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
- -p port
Defines the UDP/TCP port used by named.
port is the port number used to connect to
the remote name server. 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 used only for testing.
- -b configfile or -c configfile
Specifies the file named uses as its configuration
file. By default the configuration file is
/etc/named.conf, but the -b
or -c option allows the administrator to choose another configuration
file. Note that using -b or -c
is optional. As long as the filename used for
configfile doesn't start with a
dash, the -b or -c flag is not
required. Any filename written on the named
command line is assumed to be the configuration file, as the last
item on the command line shows.
Logs all incoming queries. named must be compiled
with the QRYLOG option set to enable this type of logging.
Turns off recursion. With this option set, the server will provide
answers only for zones for which it is an authoritative server. It
will not pursue the query through other servers or zones.
Runs named in the foreground. Normally
named is run as a background daemon.
Displays the version number. The -v switch does
not run named.
- -u username
Sets the user ID under which the server runs after initializing. By
default, named runs as root.
- -g groupname
Set the group ID under which named runs after
initializing. The group ID defaults to the master group of the user
ID under which named is run.
- -t path
Defines the path to the directory named uses when
- -w path
Defines the path of named's working
directory. The default is the current directory. The
directory option in the configuration file
overrides this setting.
C.1.1. Signal Processing
the following signals:
Causes named to reread the
named.conf file and reload the name server
database. named then continues to run with the new
configuration. If named is compiled with the
FORCED_RELOAD option, this signal forces a slave server to transfer
the zone from its master server. This signal has the same effect as
Causes named to dump its cache to
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. This signal has the same effect as
Turns on debugging; each subsequent SIGUSR1 signal increases the
level of debugging. Debugging information is written to
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. This signal has the same effect as
Turns off debugging and closes named.run. After
issuing SIGUSR2, you can examine named.run or
remove it if it is getting too large. This signal has the same effect
as ndc notrace.
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:
Writes statistics data to named.stats.
named must be compiled with -DSTATS for this
signal to work.
Writes profiling data into the directory defined by the directory
option in the named.conf file.
named must be compiled with profiling to support
Writes back the master and slave 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
Toggles logging of all incoming queries via
syslogd. named must be compiled
with the QRYLOG option to support this. This signal has the same
effect as ndc querylog.
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