named(1M) named(1M)
NAME
named, named-xfer - internet domain name server (DNS)
SYNOPSIS
named [-d debuglevel] [-q] [-r] [-p remote/local] [{-b} bootfile]
DESCRIPTION
named is the Internet domain name server. It replaces the original host
table lookup of information in the network hosts file /etc/hosts. (See
RFC1034 for more information on the Internet name-domain system.)
named-xfer is invoked by named to transfer zone data from primary
servers.
named is started at system initialization if the configuration flag named
is set on with chkconfig(1M). Without any arguments, named reads the
default boot file /etc/named.boot, read any initial data and listen for
queries.
Site-dependent options and arguments to named belong in the file
/etc/config/named.options. Options are:
-d Print debugging information. A number after the -d determines the
level of messages printed.
-q Print all sorts of query log information. Used only for debugging.
-p Use a different port number. The default is the standard port
number as listed in /etc/services, number 53. The first port number
given is the one to which we send queries. The second port number
(after the slash) is the one on which we listen. If only one is
given without a slash, that number is used for both sending and
listening.
-b Use an alternate boot file. This is optional and allows you to
specify a file with a leading dash.
-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:
directory /var/named
; type domain source host/file backup file
cache . root.cache
primary Berkeley.EDU berkeley.edu.zone
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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
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.
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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
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maximum number of zone transfers to be simultaneously initiated to any
given remote name server.
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 syslog(@SYS_OPS_EXT@) -- 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.
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 ``transfer'' directive (not shown) defines a alternate transfer
program (other than named-xfer) to be used for a specific domain. This
directive implements RFC1794. Use of the transfer directive disables
ALL record reordering for all domains being serviced by (this) named.
Use of this option should be used with care. To use transfer, named.boot
will have a transfer and secondary pair of directives for each effected
domain. Syntax of the paired transfer and secondary directives looks
like.
transfer <domain> <xfer-program>
secondary <domain> 127.0.0.1 <filename>
The master file consists of control information and a list of resource
records for objects in the zone of the forms:
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$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 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.
Each master zone file should begin with an SOA record for the zone. An
example SOA record is as follows:
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@ 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 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) or killall(1M) commands.
SIGHUP Causes server to read named.boot and reload the database.
SIGINT Dumps current data base and cache to /var/tmp/named_dump.db.
SIGABRT Dumps statistics data into /var/tmp/named.stats. Statistics
data is appended to the file.
SIGUSR1 Turns on debugging; each SIGUSR1 increments debug level.
SIGUSR2 Turns off debugging completely.
The shell script /usr/sbin/named.reload sends a SIGHUP to the server.
/usr/sbin/named.restart kills and restarts the server.
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FILES
/etc/named.boot name server configuration boot file
/var/tmp/named.run debug output
/var/tmp/named_dump.db dump of the name server database
/var/tmp/named.stats name server statistics data
SEE ALSO
kill(1), gethostbyname(3N), resolver(3N), resolv.conf(4), hostname(5).
IRIX Admin: Networking and Mail
RFC1032, RFC1033, RFC1034, RFC1035, RFC974 This version is based on the
BIND 4.9.4 patchlevel 1 release from Paul Vixie.
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