DNS on Windows Server 2003, 3rd Edition

Resource Records

The data associated with domain names is contained in resource records, or RRs. Records are divided into classes, each of which pertains to a type of network or software. Currently, there are classes for internets (any TCP/IP-based internet), networks based on the Chaosnet protocols, and networks that use Hesiod software. (Chaosnet is an old network of largely historic significance.) The internet class is by far the most popular. (We’re not really sure if anyone still uses the Chaosnet class, and use of the Hesiod class is mostly confined to MIT.) In this book, we concentrate on the internet class.

Within a class, records come in several types, which correspond to the different varieties of data that may be stored in the domain namespace. Different classes may define different record types, though some types are common to more than one class. For example, almost every class defines an address type. Each record type in a given class defines a particular record syntax to which all resource records of that class and type must adhere. (For details on resource record types and their syntaxes, see Appendix A.)

If this information seems sketchy, don’t worry—we’ll cover the records in the internet class in more detail later. The common records are described in Chapter 4, and a more comprehensive list is included as part of Appendix A.