named.boot(4) CLIX named.boot(4)
NAME
named.boot - Default boot file for Domain Name System (DNS)
DESCRIPTION
The /etc/named.boot file is an ASCII file that 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.
EXAMPLES
The following is an example of a named.boot file:
;
; 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 contains authoritative data for the domain 32.128.IN-
ADDR.ARPA, which is used to translate addresses in network 128.32 to
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named.boot(4) CLIX named.boot(4)
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 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 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 ``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 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.
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, with the following format:
$INCLUDE filename opt_domain
$ORIGIN domain
domain opt_ttl opt_class type resource_record_data
The 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
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named.boot(4) CLIX named.boot(4)
``.'', 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)
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
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.
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named.boot(4) CLIX named.boot(4)
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 replaced 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.
RELATED INFORMATION
Commands: named(8)
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