Appendix B. DNS Resource Records

This appendix provides detailed information about the DNS standard resource records (RR) used to construct domain database files. This is primarily a reference to use in conjunction with the tutorial information in Chapter 8. This information is useful to any domain administrator.

This appendix covers the most commonly used resource records. It shows the DNS Manager dialog used to enter each record and the syntax of each standard resource record (RR) as it appears in the DNS database file.

Standard Resource Records

Standard resource records define the domain data contained in the zone file. The format of standard resource records, sometimes called RRs, is defined in RFC 1033, the Domain Administrators Operations Guide. The format is:

[name] [ttl] class type data

The individual fields in the standard resource record are:


This is the name of the object affected by this resource record. The named object can be as specific as an individual host, or as general as an entire domain. The string entered for name is relative to the current domain unless a fully qualified domain name is used. Certain name values have special meaning. These are:[53]

A blank name field denotes the current named object. The current name stays in force until a new name value is encountered in the name field. This permits multiple RRs to be applied to a single object without having to repeat the object’s name for each record.


Two dots in the name field refer to the root domain. ...

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