The Structure of a Domain Name System Boot File (194513)

SUMMARY

This article discusses the structure and functionality of a boot file within the Domain Name System (DNS) schema. The first file in a DNS server is the boot file. However, the boot file is not defined in the Request for Comments (RFCs) and is not needed for a DNS server to be RFC compliant. Boot files are actually a part of the Berkeley Internet Name Domain (BIND) implementation of DNS. Boot files determine the startup behavior for DNS servers that incorporate the BIND specifications. A Microsoft Windows 2000 DNS server is compatible with the BIND implementation that supports the use of boot files.

Background Information

A Microsoft Windows NT 4.0 DNS server is compatible with the BIND implementation that supports the use of boot files. However, once the DNS server initializes and the primary zone is created, the information in the boot file is migrated into the registry. Therefore, whenever the DNS server service is initialized on the network, the boot information is read from the registry. The original boot file is copied to a backup folder after it is migrated into the registry. The backup folder is located in the %SystemRoot%\System32\Dns folder.

MORE INFORMATION

You can configure the Windows 2000 DNS service to start from a boot file, rather than from the registry. This option includes the ability to manage the zone from DNS Manager even when you start from the boot file. It is also possible to use the registry for items (such as Notify Lists) that cannot be specified in the boot file. Under Windows 2000, DNS can start using the following methods: boot file, registry boot, or directory services boot. You can modify these methods in the properties of the server in the DNS Manager.

The boot file contains the following default parameters:

Cache

This parameter specifies a file that allows the DNS service to contact name servers for the root domain. This parameter is required where the boot file is used, and the file it refers to must be present. A cache file (Cache.dns) suitable for use on the Internet is provided with Windows 2000.

Syntax : cache <filename>
Example: cache cache.dns

Primary

This parameter specifies a domain for which this name server is authoritative and a database file that contains the resource records for that domain (a zone file on the DNS server computer). Multiple instances of this parameter can exist in a boot file, one for each zone for which the server is a primary server.

Syntax : primary <domain> <filename>
Example: primary domain.com domain.com.dns

primary dev.domain.com dev.domain.com.dns

Secondary

This parameter specifies a domain for which this name server is authoritative, and a list of master server IP addresses from which to download the zone information, rather than from a local file. This parameter also defines the name of the local file to use for caching transferred zone data. Multiple secondary records can exist in the boot file, one for each zone for which the server is a secondary server.

Syntax : secondary <domain> <hostlist> <local filename>
Example: secondary test.domain.com 10.55.200.100 test.domain.com.dns

Forwarders

This parameter specifies another server that can try to resolve recursive queries.

Syntax : forwarders <hostlist>
Example: forwarders 10.55.200.100 10.55.200.101

Slave

This parameter specifies that the use of forwarders is the only possible way to resolve queries. Slave servers can follow only a forwarder's parameter.

Syntax : slave
Example: forwarders 10.55.200.100 10.55.200.101

slave