path: root/usr.sbin/named/named.8

.\" Copyright (c) 1985, 1991 The Regents of the University of California.
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.\"     from: @(#)named.8	6.9 (Berkeley) 3/16/91
.\"	$Id: named.8,v 1.1 1995/10/18 08:47:50 deraadt Exp $
.\"
.Dd March 16, 1991
.Dt NAMED 8
.Os BSD 4
.Sh NAME
.Nm named
.Nd Internet domain name server
.Sh SYNOPSIS
.Nm named
.Op Fl d Ar debuglevel
.Op Fl p Ar port#
.Oo Op Fl b
.Ar bootfile Oc
.Sh DESCRIPTION
.Nm Named
is the Internet domain name server.
See
.%T RFC883
for more information on the Internet name-domain system.
Without any arguments,
.Nm named
will read the default boot file
.Pa /etc/named.boot ,
read any initial data and listen for queries.
.Pp
Options are:
.Bl -tag -width Ds
.It Fl d
Print debugging information.
A number after the
.Fl d
determines the level of
messages printed.
.It Fl p
Use a different port number.  The default is the standard port number
as listed in
.Pa /etc/services .
.It Fl b
Use an alternate boot file.  This is optional and allows you to
specify a file with a leading dash.
.El
.Pp
Any additional argument is taken as the name of the boot file.
The boot file contains information about where the name server is to get
its initial data.  If multiple boot files are specified, only the last
is used.
Lines in the boot file cannot be continued on subsequent lines.
The following is a small example:
.Bd -literal
;
;	boot file for name server
;
directory	/etc/namedb

; type	domain	source host/file		      backup file

cache	.					      root.cache
primary   Berkeley.EDU          berkeley.edu.zone
primary   32.128.IN-ADDR.ARPA   ucbhosts.rev
secondary CC.Berkeley.EDU 128.32.137.8 128.32.137.3 cc.zone.bak
secondary 6.32.128.IN-ADDR.ARPA 128.32.137.8 128.32.137.3 cc.rev.bak
primary   0.0.127.IN-ADDR.ARPA localhost.rev
forwarders 10.0.0.78 10.2.0.78
; slave
.Ed
.Pp
The ``directory'' line causes the server to change its
working directory to the directory specified.  This can
be important for the correct processing of
.Li $INCLUDE
files
in primary zone files.
.Pp
The
.Dq cache
line specifies that data in
.Dq Pa root.cache
is to be
placed in the backup cache.
Its main use is to specify data such as locations of root domain servers.
This cache is not used during normal operation,
but is used as
.Dq hints
to find the current root servers.
The file
.Dq Pa root.cache
is in the same format as
.Dq Pa berkeley.edu.zone .
There can be more than one
.Dq cache
file specified.
.\"The first such file will be updated under certain conditions to snapshot the
.\"cache (see
.\" .Dv SIGQUIT
.\" below).
.\"The cache line can also have an optional interval argument after
.\"the filename.
.\"If an interval is listed,
.\"it requests the nameserver to dump the cache contents
.\"at that interval (in seconds).
.\"The example above requests the nameserver to dump the cache content
.\"every 3600 seconds (once an hour).
.\"The use of automatic cache file updates is not currently recommended
.\"because of the way the cache is currently managed by the server;
.\"although the entire cache will be dumped for later reloading,
.\"most of the cache contents will be ignored when reloaded.
.\"The exact dump interval will vary
.\"based on the minimum maintence interval time which is typically about
.\"5 minutes.
The cache files are processed in such a way as to preserve the
time-to-live's
of data dumped out.  Data for the root nameservers is kept artificially
valid if necessary.
.Pp
The first
.Dq primary
line states that the file
.Dq Pa berkeley.edu.zone
contains
authoritative data for the
.Dq Berkeley. Ns Em EDU
zone.
The file
.Dq Pa berkeley.edu.zone
contains data in the master file format described in
.%T RFC883 .
All domain names are relative to the origin, in this
case,
.Dq Berkeley. Ns Em EDU
(see below for a more detailed description).
The second
.Dq primary
line states that the file
.Dq Pa ucbhosts.rev
contains
authoritative data for the domain
.Dq 32.128.IN-ADDR.ARPA ,
which is used
to translate addresses in network 128.32 to hostnames.
Each master file should begin with an
.Tn SOA
record for the zone
(see below).
.Pp
The first ``secondary'' line specifies that all authoritative data
under
.Dq CC.Berkeley. Ns Em EDU
is to be transferred from the name server
at 128.32.137.8.  If the transfer fails it will try 128.32.137.3 and
continue trying the addresses, up to 10, listed on this line.
The secondary copy is also authoritative for the specified domain.
The first non-dotted-quad address on this line will be taken
as a filename in which to backup the transfered zone.
The name server will load the zone from this backup file if it exists
when it boots, providing a complete copy even if the master servers
are unreachable.
Whenever a new copy of the domain is received by automatic zone transfer
from one of the master servers, this file will be updated.
The second
.Dq secondary
line states that the address-to-hostname
mapping for the subnet 128.32.136 should be obtained from the same list
of master servers as the previous zone.
.Pp
The
.Dq forwarders
line specifies the addresses of sitewide servers
that will accept recursive queries from other servers.
If the boot file specifies one or more forwarders, then the
server will send all queries for data not in the cache to the forwarders first.
Each forwarder will be asked in turn until an answer is returned
or the list is exhausted.  If no answer is forthcoming from a
forwarder, the server will continue as it would have without
the forwarders line unless it is in ``slave'' mode.
The forwarding facility is useful
to cause a large sitewide cache to be generated on a master,
and to reduce traffic over links to outside servers.
It can also be used to allow servers to run that do not have
access directly to the Internet, but wish to act as though
they do.
.Pp
The ``slave'' line (shown commented out) is used to put the server
in slave mode.  In this mode, the server will only make queries to
forwarders.  This option is normally used on machine that wish to
run a server but for physical or administrative reasons cannot
be given access to the Internet, but have access to a host that
does have access.
.Pp
The ``sortlist'' line can be used to indicate networks that are to be
preferred over other, unlisted networks.
Queries for host addresses from hosts on the same network as the server
will receive responses with local network addresses listed first,
then addresses on the sort list, then other addresses.
This line is only acted on at initial startup.
When reloading the nameserver with
a
.Dv SIGHUP ,
this line will be ignored.
.Pp
The master file consists of control information
and a list of resource records for objects in the zone
of the forms:
.Bd -literal
$INCLUDE <filename> <opt_domain>
$ORIGIN <domain>
<domain> <opt_ttl> <opt_class> <type> <resource_record_data>
.Ed
.Pp
where
.Em domain
is
.Ql \&.
for root,
.Ql \&@
for the current origin, or a standard domain
name. If
.Em domain
is a standard domain name that does not end with
.Ql \&. ,
the current origin
is appended to the domain. Domain names ending with
.Ql \&.
are
unmodified.
The
.Em opt_domain
field is used to define an origin for the data in an included file.
It is equivalent to placing a
.Li $ORIGIN
statement before the first
line of the included file.  The field is optional.
Neither the
.Em opt_domain
field nor
.Li $ORIGIN
statements in the included file modify the current origin
for this file.
The
.Em opt_ttl
field is an optional integer number for the time-to-live field.
It defaults to zero, meaning the minimum value specified in the
SOA record for the zone.
The
.Em opt_class
field is the object address type; currently only one type is supported,
.Sy IN ,
for objects connected to the
.Tn DARPA
Internet. 
The
.Em type
field contains one of the following tokens; the data expected in the
.Em resource_record_data
field is in parentheses.
.Bl -tag -width Fl
.It A
a host address (dotted quad)
.It \&NS
an authoritative name server (domain)
.It \&MX
a mail exchanger (domain)
.It CNAME
the canonical name for an alias (domain)
.It SOA
marks the start of a zone of authority (domain of originating host,
domain address of maintainer, a serial number and the following
parameters in seconds: refresh, retry, expire and minimum TTL
(see
.%T RFC883 ) )
.It \&MB
a mailbox domain name (domain)
.It \&MG
a mail group member (domain)
.It \&MR
a mail rename domain name (domain)
.It NULL
ra null resource record (no format or data)
.It \&WKS
a well know service description (not implemented yet)
.It \&PTR
a domain name pointer (domain)
.It HINFO
host information (cpu_type OS_type )
.It MINFO
mailbox or mail list information (request_domain error_domain)
.El
.Pp
Resource records normally end at the end of a line,
but may be continued across lines between opening and closing parentheses.
Comments are introduced by semicolons and continue to the end of the line.
.Pp
Each master zone file should begin with an SOA
record for the zone.
An example SOA
record is as follows:
.Bd -literal
@  IN  SOA  ucbvax.Berkeley.EDU. rwh.ucbvax.Berkeley.EDU. (
                             2.89	; serial
                             10800	; refresh
                             3600	; retry
                             3600000	; expire
                             86400 )	; minimum
.Ed
.Pp
The SOA
lists a serial number, which should be changed each time the master
file is changed.
Secondary servers check the serial number at intervals specified by the refresh
time in seconds; if the serial number changes, a zone transfer will be done
to load the new data.
If a master server cannot be contacted when a refresh is due, the retry time
specifies the interval at which refreshes should be attempted until successful.
If a master server cannot be contacted within the interval given by the
expire time, all data from the zone is discarded by secondary servers.
The minimum value is the time-to-live used by records in the file
with no explicit time-to-live value.
.Sh NOTES
The boot file directives ``domain'' and ``suffixes'' have been
obsoleted by a more useful resolver based implementation of
suffixing for partially qualified domain names.  The prior mechanisms
could fail under a number of situations, especially when then local
nameserver did not have complete information.
.Pp
The following signals have the specified effect when sent to the
server process using the
.Xr kill 1
command.
.Bl -tag -width Fl
.It Dv SIGHUP
Causes server to read
.Pa named.boot
and reload database.
.It Dv SIGINT
Dumps current data base and cache to
.Pa /var/tmp/named_dump.db
.\".IP
.\" .Dv SIGQUIT
.\"Causes the server to checkpoint the cache into the first ``cache'' file.
.It Dv SIGIOT
Dumps statistics data into
.Pa /var/tmp/named.stats
if the server is
compiled
.Dv \-DSTATS .
Statistics data is appended to the file.
.It Dv SIGSYS
Dumps the profiling data in
.Pa /var/tmp
if the server is compiled
with profiling (server forks, chdirs and exits).
.It Dv SIGTERM
Dumps the primary and secondary database files.
Used to save modified data on shutdown if the
server is compiled with dynamic updating enabled.
.It Dv SIGUSR1
Turns on debugging; each
.Dv SIGUSR1
increments debug level.
.Pf ( Dv SIGEMT
on older systems without
.Dv SIGUSR1 )
.It Dv SIGUSR2
Turns off debugging completely.
.Pf ( Dv SIGFPE
on older systems without
.Dv SIGUSR2 )
.El
.Sh FILES
.Bl -tag -width /var/tmp/named_dump.db -compact
.It Pa /etc/named.boot
name server configuration boot file
.It Pa /var/run/named.pid
the process id
.It Pa /var/tmp/named.run
debug output
.It Pa /var/tmp/named_dump.db
dump of the name server database
.It Pa /var/tmp/named.stats
nameserver statistics data
.El
.Sh SEE ALSO
.Xr kill 1 ,
.Xr gethostbyname 3 ,
.Xr signal 3 ,
.Xr resolver 3 ,
.Xr resolv.conf 5 ,
.Xr hostname 7 ,
.Rs
.%T RFC882
.Re
.Rs
.%T RFC883
.Re
.Rs
.%T RFC973
.Re
.Rs
.%T RFC974
.Re
.Rs
.%T "Name Server Operations Guide for BIND"
.Re
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.3 .