NAMED(8)

NAME
named - Internet domain name server

SYNOPSIS
named [ -d debuglevel ] [ -p port#[/localport#] ] [{-b} bootfile ] [ -q ] [ -r ]

DESCRIPTION
Named is the Internet domain name server. See RFC's 1033, 1034, and 1035 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 nonstandard port numbers. The default is the standard port number as returned by getservbyname(3) for service ``domain''. The argument can specify two port numbers separated by a slash (``/'') in which case the first port is that used when contacting remote servers, and the second one is the service port bound by the local instance of named. This is used mostly for debugging purposes.

-b  Use an alternate boot file. This is optional and allows you to specify a file with a leading dash.

-q  Trace all incoming queries if named has been compiled with QRYLOG defined. NOTE: this option is deprecated in favour of the boot file directive ``options query-log''.

-r  Turns recursion off in the server. Answers can come only from local (primary or secondary) zones. This can be used on root servers. NOTE: this option is deprecated in favour of the boot file directive ``options no-recursion''.

Any additional argument is taken as the name of the boot file. If multiple boot files are specified, only the last is used.

The boot file contains information about where the name server is to get its initial data. 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/adm/named
; 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
limit	transfers-in 10
limit	datasize 64M
limit	files 256
options	forward-only query-log fake-iquery
check-names	primary fail
check-names	secondary warn
check-names	response ignore
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 ``root.cache'' file should be retrieved periodically from FTP.RS.INTERNIC.NET since it contains a list of root servers, and this list changes periodically.

The first example ``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 RFC 883. 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'' contains 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 example ``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 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 transferred 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. If no file name is given, a temporary file will be used, and will be deleted after each successful zone transfer. This is not recommended since it is a needless waste of bandwidth. The second example ``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 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 ``forward-only'' 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 direct access to the Internet, but wish to look up exterior names anyway.

The ``slave'' line (deprecated) is allowed for backward compatibility. Its meaning is identical to ``options forward-only''.

The ``sortlist'' line can be used to indicate networks that are to be preferred over other 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.

The ``xfrnets'' directive (not shown) can be used to implement primitive access control. If this directive is given, then your name server will only answer zone transfer requests from hosts which are on networks listed in your ``xfrnets'' directives. This directive may also be given as ``tcplist'' for compatibility with older, interim servers.

The ``include'' directive (not shown) can be used to process the contents of some other file as though they appeared in place of the ``include'' directive. This is useful if you have a lot of zones or if you have logical groupings of zones which are maintained by different people. The ``include'' directive takes one argument, that being the name of the file whose contents are to be included. No quotes are necessary around the file name.

The ``bogusns'' directive (not shown) tells BIND that no queries are to be sent to the specified name server addresses (which are specified as dotted quads, not as domain names). This is useful when you know that some popular server has bad data in a zone or cache, and you want to avoid contamination while the problem is being fixed.

The ``limit'' directive can be used to change BIND's internal limits, some of which (datasize, for example) are implemented by the system and others (like transfers-in) by BIND itself. The number following the limit name can be scaled by postfixing a ``k,'' ``m,'' or ``g'' for kilobytes, megabytes, and gigabytes respectively. datasize's argument sets the process data size enforced by the kernel. Note: not all systems provide a call to implement this -- on such systems, the use of the datasize parameter of ``limit'' will result in a warning message. transfers-in's argument is the number of named-xfer subprocesses which BIND will spawn at any one time. transfers-per-ns's argument is the maximum number of zone transfers to be simultaneously initiated to any given remote name server. files's argument sets the number of file descriptors available to the process. Note: not all systems provide a call to implement this -- on such systems, the use of the files parameter of ``limit'' will result in a warning message.

The ``options'' directive introduces a boolean specifier that changes the behaviour of BIND. More than one option can be specified in a single directive. The currently defined options are as follows: no-recursion, which will cause BIND to answer with a referral rather than actual data whenever it receives a query for a name it is not authoritative for -- don't set this on a server that is listed in any host's resolv.conf file; no-fetch-glue, which keeps BIND from fetching missing glue when constructing the ``additional data'' section of a response; this can be used in conjunction with no-recursion to prevent BIND's cache from ever growing in size or becoming corrupted; query-log, which causes all queries to be logged via syslogd(8) -- this is a lot of data, don't turn it on lightly; forward-only, which causes the server to query only its forwarders -- this option is normally used on machine that wishes to run a server but for physical or administrative reasons cannot be given access to the Internet; and fake-iquery, which tells BIND to send back a useless and bogus reply to ``inverse queries'' rather than responding with an error -- this is helpful if you have a lot of microcomputers or SunOS hosts or both.

The ``check-names'' directive tells BIND to check names in either ``primary'' or ``secondary'' zone files, or in messages (``response'') received during recursion (for example, those which would be forwarded back to a firewalled requestor). For each type of name, BIND can be told to ``fail'', such that a zone would not be loaded or a response would not be cached or forwarded, or merely ``warn'' which would cause a message to be emitted in the system operations logs, or to ``ignore'' the badness of a name and process it in the traditional fashion. Names are considered good if they match RFC 952's expectations (if they are host names), or if they consist only of printable ASCII characters (if they are not host names).

The ``max-fetch'' directive (not shown) is allowed for backward compatibility; its meaning is identical to ``limit transfers-in''.

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 specified 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), preceded by a preference value (0..32767), with lower numeric values representing higher logical preferences.

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 following parameters in seconds: refresh, retry, expire and minimum TTL (see RFC 883)).

NULL
    a null resource record (no format or data)

RP  a Responsible Person for some domain name (mailbox, TXT-referral)

PTR a domain name pointer (domain)

HINFO
    host information (cpu_type OS_type)

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.

Note that there are other resource record types, not shown here. You should consult the BIND Operations Guide (``BOG'') for the complete list. Some resource record types may have been standardized in newer RFC's but not yet implemented in this version of BIND.

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. (
	1989020501	; serial
	10800	; refresh
	3600	; retry
	3600000	; expire
	86400 )	; minimum

The SOA specifies a serial number, which should be changed each time the master file is changed. Note that the serial number can be given as a dotted number, but this is a very unwise thing to do since the translation to normal integers is via concatenation rather than multiplication and addition. You can spell out the year, month, day of month, and 0..99 version number and still fit inside the unsigned 32-bit size of this field. It's true that we will have to rethink this strategy in the year 4294 (Greg.) but we're not worried about it. 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. 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 (``TTL'') 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 the database. If the server is built with the FORCED_RELOAD compile-time option, then SIGHUP will also cause the server to check the serial number on all secondary zones. Normally the serial numbers are only checked at the SOA-specified intervals.

SIGINT
    Dumps the current data base and cache to /var/tmp/named_dump.db

SIGIOT
    Dumps statistics data into /var/tmp/named.stats if the server is compiled with -DSTATS. Statistics data is appended to the file. Some systems use SIGABRT rather than SIGIOT for this.

SIGSYS
    Dumps the profiling data in /var/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)

SIGWINCH
    Toggles logging of all incoming queries via syslogd(8) (requires server to have been built with the QRYLOG option).

FILES
/etc/named.boot	name server configuration boot file
/etc/named.pid	the process id (on older systems)
/var/run/named.pid	the process id (on newer systems)
/var/tmp/named_dump.db	dump of the name server database
/var/tmp/named.run	debug output
/var/tmp/named.stats	nameserver statistics data

SEE ALSO
kill(1), gethostbyname(3), signal(2), resolver(3), resolver(5), hostname(7), RFC 882, RFC 883, RFC 973, RFC 974, RFC 1033, RFC 1034, RFC 1035, RFC 1123, Name Server Operations Guide for BIND