Appendix A. DNS Message Format and Resource Records

This appendix outlines the format of DNS messages and enumerates all the resource record types. The resource records are shown in their textual format, as you would specify them in a zone data file, and in their binary format, as they appear in DNS messages. You'll find a few resource records here that weren't covered in the book because they are experimental or obsolete.

We've included the portions of RFC 1035, written by Paul Mockapetris, that deal with the textual format of master files (what we called zone data files in the book) or with the DNS message format (for those of you who need to parse DNS packets).