Zone Datafile Format

The format of zone datafiles is specified in the DNS standards. That means all name servers, whether Microsoft DNS Server or the BIND name server, can read each other’s zone datafiles.

You’ve probably already guessed that the semicolon is the comment character. It can appear anywhere on a line, and anything to the right is considered a comment and is ignored by the name server. Blank lines are okay, too.

Each resource record must start in the first column of the file—no preceding whitespace. (Don’t be confused by the examples in this book, which are indented because of the way the book is formatted.) Resource records are case-insensitive—you can use uppercase or lowercase. The name server doesn’t preserve the case, though. It matches the case of the reply to the case of the query. For example, if a record is written as terminator in the zone datafile but you query for Terminator, the server responds with Terminator.

Resource records are broken up into fields, with any amount of whitespace (tabs or spaces) separating the fields.

The first field, called the owner, is the domain name of the record. Put another way, it’s the node in the namespace to which the resource record is attached. You’ve seen the domain name on the left side of the right pane of the DNS console.

The next field in our examples is the class, IN, which stands for Internet. Other classes exist, but none of them are currently in widespread use. Our examples use only the IN class.

The field after ...

Get DNS on Windows Server 2003, 3rd Edition now with the O’Reilly learning platform.

O’Reilly members experience live online training, plus books, videos, and digital content from nearly 200 publishers.