ABBDA: Zone File

Zone File

Explanation 1

A zone file is stored on a name server and provides information about one or more domain names. Each zone file contains a list of DNS records with mappings between domain names and IP addresses. These records define the IP address of a domain name, the reverse lookup of an IP to other domains, and contain DNS and mail server information.

Because zone files are plain text files, they can be edited quickly and easily. However, this also means that if unauthorized users gain access to zone files, the files can be easily modified. This could cause websites to not respond, or worse yet, redirect to the wrong Web server. For this reason, it is important to keep the zone files on a highly secured server and always have a recent backup of zone files on another machine.

Explanation 2

A zone file is a small set of instructions for resolving specified Internet domain names to the appropriate number form of an Internet Protocol address (an IP address). These instructions are ordinarily quite simple and reside in a file on the server that administers a site. Zone files can be used with HTTP (Hypertext Transfer Protocol), FTP (File Transfer Protocol), or SMTP (Simple Mail Transfer Protocol) addresses.

Ideally, a Web zone file should allow resolution of domains either with or without the three letters www. For example, both of these Internet addresses yield the same result:

http://www.whatis.com

http://whatis.com

This indicates that the server administrator has written the zone file properly for this Web domain.

Explanation 3

Zone files contain information about a namespace and are stored in the named working directory, /var/named/, by default. Each zone file is named according to the file option data in the zone statement, usually in a way that relates to the domain in question and identifies the file as containing zone data, such as example.com.zone.

Each zone file may contain directives and resource records. Directives tell the nameserver to perform tasks or apply special settings to the zone. Resource records define the parameters of the zone and assign identities to individual hosts. Directives are optional, but resource records are required to provide name service to a zone.

All directives and resource records should go on their own individual lines.

Comments can be placed after semicolon characters (;) in zone files.