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BIND's Boot File

The boot file is first read when named starts up. It tells the server what type of server it is, which zones it has authority over, and where to get its initial data. The default name of this file is /etc/named.boot. The template for this file is called /var/named/Examples/named.boot.master (for primary server) and named.boot.slave (for secondary server).

To use a different file, create or modify the /etc/config/named.options file with this entry:

-b other-bootfile-name
The recognized boot file structures are described in the subsections that follow.

Directory

The directory line specifies the directory in which the name server should run, allowing the other filenames in the boot file to use relative pathnames.

directory /var/named
This entry is required. It makes sure named is in the proper directory when you try to include files by relative pathnames with $INCLUDE. It also allows named to run in a location that is reasonable for dumping core, if necessary.

Primary Master

The line in the boot file that designates a primary server for a zone looks like this:

primary   Berkeley.EDU   named.hosts
The first field specifies that the server is a primary one for the zone stated in the second field. The third field is the name of the file from which the data is read.

Secondary Master

The line for a secondary server is similar to that for the primary, except that it lists addresses of other servers (usually primary servers) from which the zone data is obtained. For example:

secondary  Berkeley.EDU 128.32.0.10 128.32.0.4 ucbhosts.bak
The first field specifies that the server is a secondary master server for the zone stated in the second field. The two network addresses specify the name servers that are primary for the zone. The secondary server gets its data across the network from the listed servers. It tries each server in the order listed until it successfully receives the data from a listed server.

If a file name is present after the list of primary servers, data for the zone is saved in that file. When the server first starts, it loads the data from the backup file if possible, and consults a primary server to check that the zone information is still up to date.

Caching-Only Server

All servers should have a line like this one in the boot file to prime the name server's cache: 

cache   .   root.cache
All listed cache files are read when named starts up. Valid values are reinstated in the cache, and the root name server information in the cache files is always used to handle initial queries.

The name server needs to know the servers that are the authoritative name servers for the root domain of the network. The root.cache file primes the server's cache with the addresses of these higher authorities. This file uses the Standard Resource Record format (or Master File format) described in detail in Appendix F.

You do not need a special line to designate that a server is a caching server. What denotes a caching-only server is the absence of authority lines, such as secondary or primary, in the boot file.

Forwarders

Any server can make use of forwarders. For example, a server capable of processing recursive queries may try resolving queries on behalf of other stations. The forwarders command specifies forwarders by Internet address as follows:

forwarders    128.32.0.10     128.32.0.4

Slave Mode

You can use slave mode if, because of limited network access, use of forwarders is the only way to resolve queries. You can also use slave mode if you wish to prevent the name server from using forwarders other than those listed. Slave mode is activated by the following command in the boot file:

slave
If you use slave, you must specify forwarders. In slave mode, the server forwards each query to each of the forwarders until an answer is found or the list of forwarders is exhausted.

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