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AIX Version 4 Files Reference

named.boot File Format for TCP/IP


Defines how the named daemon initializes the DOMAIN name server file.


The /etc/named.boot file is the default configuration (or boot) file for the named server. If the named daemon is started without specifying an alternate file, the named daemon reads this file for information on how to set up the local name server file. This file is directly accessed by local kernel resolver routines on the name server host and is indirectly accessed through named service requests by remote hosts.

Note: The named daemon reads the startup file only when the named daemon starts or when the named daemon receives an SRC refresh command or a SIGHUP signal.

The records in the named.boot file tell the named daemon what type of server it is, which domains it has authority over (its zones of authority), and where to get the data for initially setting up its name resolution database.

Any data files referenced in the named startup file must be in Standard Resource Record Format. These data files can have any name. However, for convenience in maintaining the named database, they are generally given names in the following form: /etc/named.extension. The general format of named data files is described in DOMAIN Data File, DOMAIN Reverse Data File, DOMAIN Cache File, and DOMAIN Local File.

Comments in the boot file begin with a ; (semicolon) and end at the end of the line.

The named boot file is organized in lines. Valid lines and their formats in the named.boot file are:

cache Domain FileName Indicates that the local named server is a caching name server for the domain specified in the Domain parameter and that the named daemon is to get the data describing the domain from the file specified in the FileName parameter.

The name server first needs to know the root name server (the name server on the network with the highest authority). The root name server is established in the named.boot file by specifying the root server file name (named.ca) as the cache for this name server.

Note: The named daemon does not provide other hosts with the information contained in a cache file. Cache files are usually used for listing the name servers for domains higher than the local domain.

An example of the cache line follows:

cache            .           /etc/named.ca
directory Path 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 as well as in locating data files for the name server. An example of the directory line follows:
directory /usr/local/domain
Note: If no directory line is specified here, the full path name must be specified in all other lines specifying files.
forwarders IPAddresses The forwarders line specifies the addresses of sitewide servers that accept recursive queries from other servers. If the boot file specifies one or more forwarders, then the server sends all queries for data not in the cache to the forwarders first. Each forwarder is asked in turn until an answer is returned or the list is exhausted. If no answer is forthcoming from a forwarder, the server continues 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 reduce traffic over links to outside servers. It is also used to allow servers to run that do not have access directly to the Internet, but wish to act as though they do. An example of a forwarders line follows:

Note: For each forwarder specified in the named.boot file, set up an NS (name server) entry in the DOMAIN data file.

The forwarders line forwards a query if all of the following conditions are met:

  • The query is not in the local database.
  • The local name server (containing the forwarders line) is the start of authority for the domain of the incoming query.
  • A name server resource record is in the cache or hints database on the local name server.

The following example of the named.boot file contains a forwarders line:

cache          .                /etc/named.kent.cache

In the example, the /etc/named.kent.cache file may contain the following data:

.       99999999   IN   NS   C.NYSER.NET.
;  Prep the cache (hotwire the addresses).
C.NYSER.NET.        99999999   IN   A

The name server resource record in the /etc/named.kent.cache file is placed in the cache of the local name server. An incoming query is forwarded to If the name server at cannot be reached or cannot find the query, the query will be sent to the name server resource records.

If the named.boot file contains the slave line, the forwarders line will produce the same result, except when the name server at cannot be reached or cannot find the query. In this case, the query will not be sent to the name server resource records.

Note: Although a slave forwarder does not use the name server resource records, they must be in the cache or hints database for forwarding or slave forwarding to occur.
primary Domain FileName Indicates that the local named server is the primary name server for the domain specified in the Domain parameter and that the named daemon is to get the data describing the domain from the file specified in the FileName parameter. An example of the primary line follows:
primary abc.aus.century.com   /etc/named.abcdata
secondary Domain IPAddresses FileName
                          Indicates that the local named server is a secondary name server for the domain specified in the Domain parameter and that the named daemon is to get the data describing the domain from one or more remote primary name servers using the Internet address or addresses specified in the IPAddresses parameter. The named daemon tries each address in the order listed until it successfully receives the data from one of the name servers.

The named daemon performs backup for information it receives from the primary name server in the file specified in the FileName parameter. Whenever a new copy of the domain information is received from one of the primary servers, this file is updated. The daemon uses this file as its initial cache any time the primary name server is down. In the secondary line, the FileName parameter is required. Examples of the secondary line follow:

secondary abc.aus.century.com\
secondary 201.9.192.in-addr.arpa\
slave The slave line is used to put the server in slave mode. In this mode, the server only makes queries to forwarders. This option is normally used on machines 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 to the Internet. The format of the slave line follows:

See the forwarders line information for more details on using the slave line.

Note: You can achieve a similar configuration without running a slave server. To do so, create an /etc/resolv.conf file that contains name server lines pointing to the forwarders you wish to use.
sortlist Indicates networks that take precedence over other networks. Requests for name resolution from a host on the same network as the server receive local network addresses listed first, addresses on the sortlist listed second, and all other addresses listed last. The sortlist line is only acted upon at initial startup. When reloading the name server with a SIGHUP signal, this line will be ignored.


The following examples show the various ways to use the named boot file. In these examples, two networks are represented: abc  and xyz .

Network abc consists of:

Network xyz consists of:

  1. The /etc/named.boot file for gobi.abc , the primary name server for network abc , contains these entries:
    ;boot file for abc primary server  - gobi.abc
    ;type         domain                     source file or host
    primary         abc                      /etc/named.abcdata
    primary         201.9.192.inn-addr.arpa  /etc/named.abcrev
    primary         0.0.127.in-addr.arpa     /etc/named.abclocal
  2. The /etc/named.boot file for kalahari.xyz , the primary name server for network xyz , contains these entries:
    ;boot file for abc primary server  -  kalahari.xyz
    ;type         domain                     source file or host
    primary         xyz                      /etc/named.xyzdata
    primary         9.160.in-addr.arpa       /etc/named.xyzrev
    primary         0.0.127.in-addr.arpa     /etc/named.xyz.local
  3. The /etc/named.boot file for sandy , the secondary name server for networks abc and xyz , contains the following entries:
    ;boot file for secondary server for abc and xyz - sandy
    ;type         domain                     source file or host
    directory  /etc
    secondary  abc             named.abcdata.bak
    secondary  xyz             named.xyzdata.bak
    secondary  201.9.192.in-addr.arpa  named.abcrev.bak
    secondary  9.160.in-addr.arpa  named.xyzrev.bak
    primary    0.0.127.in-addr.arpa                 named.seclocal
  4. The /etc/named.boot file for sahara , a cache-only name server for the network xyz , contains the following entries:
    ;boot file for cache-only server for xyz - sahara
    ;type         domain                     source file or host
    cache           .                        /etc/named.ca
    primary         0.0.127.in-addr.arpa     /etc/named.calocal

Implementation Specifics

This file is part of TCP/IP in Network Support Facilities in Base Operating System (BOS) Runtime.


/usr/samples/tcpip/named.boot Contains the sample named.boot file. This file also contains directions for its use.

Related Information

The named daemon.

The DOMAIN cache file format, DOMAIN local file format, DOMAIN data file format, DOMAIN Reverse data file format, rc.tcpip file format.

Configuring a Primary Name Server and Naming for TCP/IP in AIX Version 4.3 System Management Guide: Communications and Networks.

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