NAMED(8) System Manager's Manual NAMED(8)
NAME
named - Internet domain name server
SYNOPSIS
named [ -d debuglevel ] [ -p port# ] [{-b} bootfile ]
DESCRIPTION
Named is the Internet domain name server. See RFC883 for more information on the Internet name-domain system. Without any arguments,
named will read the default boot file /etc/named.boot, read any initial data and listen for queries.
Options are:
-d Print debugging information. A number after the ``d'' determines the level of messages printed.
-p Use a different port number. The default is the standard port number as listed in /etc/services.
-b Use an alternate boot file. This is optional and allows you to specify a file with a leading dash.
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:
;
; boot file for name server
;
directory /usr/local/domain
; 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
The ``directory'' line causes the server to change its working directory to the directory specified. This can be important for the correct
processing of $INCLUDE files in primary zone files.
The ``cache'' line specifies that data in ``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 ``hints'' to find the current root
servers. The file ``root.cache'' is in the same format as ``berkeley.edu.zone''. There can be more than one ``cache'' file specified.
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.
The first ``primary'' line states that the file ``berkeley.edu.zone'' contains authoritative data for the ``Berkeley.EDU'' zone. The file
``berkeley.edu.zone'' contains data in the master file format described in RFC883. All domain names are relative to the origin, in this
case, ``Berkeley.EDU'' (see below for a more detailed description). The second ``primary'' line states that the file ``ucbhosts.rev'' con-
tains authoritative data for the domain ``32.128.IN-ADDR.ARPA,'' which is used to translate addresses in network 128.32 to hostnames. Each
master file should begin with an SOA record for the zone (see below).
The first ``secondary'' line specifies that all authoritative data under ``CC.Berkeley.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 sec-
ondary 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 com-
plete 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 ``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.
The ``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 for-
warder 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.
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 for-
warders. 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.
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 SIGHUP, this line will be
ignored.
The master file consists of control information and a list of resource records for objects in the zone of the forms:
$INCLUDE <filename> <opt_domain>
$ORIGIN <domain>
<domain> <opt_ttl> <opt_class> <type> <resource_record_data>
where domain is "." for root, "@" for the current origin, or a standard domain name. If domain is a standard domain name that does not end
with ``.'', the current origin is appended to the domain. Domain names ending with ``.'' are unmodified. The opt_domain field is used to
define an origin for the data in an included file. It is equivalent to placing a $ORIGIN statement before the first line of the included
file. The field is optional. Neither the opt_domain field nor $ORIGIN statements in the included file modify the current origin for this
file. The opt_ttl field is an optional integer number for the time-to-live field. It defaults to zero, meaning the minimum value speci-
fied in the SOA record for the zone. The opt_class field is the object address type; currently only one type is supported, IN, for objects
connected to the DARPA Internet. The type field contains one of the following tokens; the data expected in the resource_record_data field
is in parentheses.
A a host address (dotted quad)
NS an authoritative name server (domain)
MX a mail exchanger (domain)
CNAME the canonical name for an alias (domain)
SOA marks the start of a zone of authority (domain of originating host, domain address of maintainer, a serial number and the follow-
ing parameters in seconds: refresh, retry, expire and minimum TTL (see RFC883))
MB a mailbox domain name (domain)
MG a mail group member (domain)
MR a mail rename domain name (domain)
NULL a null resource record (no format or data)
WKS a well know service description (not implemented yet)
PTR a domain name pointer (domain)
HINFO host information (cpu_type OS_type)
MINFO mailbox or mail list information (request_domain error_domain)
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.
Each master zone file should begin with an SOA record for the zone. An example SOA record is as follows:
@ IN SOA ucbvax.Berkeley.EDU. rwh.ucbvax.Berkeley.EDU. (
2.89 ; serial
10800 ; refresh
3600 ; retry
3600000 ; expire
86400 ) ; minimum
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.
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.
The following signals have the specified effect when sent to the server process using the kill(1) command.
SIGHUP Causes server to read named.boot and reload database.
SIGINT Dumps current data base and cache to /usr/tmp/named_dump.db
SIGIOT Dumps statistics data into /usr/tmp/named.stats if the server is compiled -DSTATS. Statistics data is appended to the file.
SIGSYS Dumps the profiling data in /usr/tmp if the server is compiled with profiling (server forks, chdirs and exits).
SIGTERM
Dumps the primary and secondary database files. Used to save modified data on shutdown if the server is compiled with dynamic
updating enabled.
SIGUSR1
Turns on debugging; each SIGUSR1 increments debug level. (SIGEMT on older systems without SIGUSR1)
SIGUSR2
Turns off debugging completely. (SIGFPE on older systems without SIGUSR2)
FILES
/etc/named.boot name server configuration boot file
/var/run/named.pid the process id
/usr/tmp/named.run debug output
/usr/tmp/named_dump.db dump of the name server database
/usr/tmp/named.stats nameserver statistics data
SEE ALSO
kill(1), gethostbyname(3), signal(3), resolver(3), resolver(5), hostname(7), RFC882, RFC883, RFC973, RFC974, Name Server Operations Guide
for BIND
4th Berkeley Distribution February 28, 1988 NAMED(8)