This chapter describes the binary messages and resource record (RR) formats that pass between DNS servers. These messages comprise what is sometimes called the wire format because it is the format sent across the network, or wire, in the understated slang of the network professional. While it's primarily a reference section with copious descriptions of bits and bytes, this chapter is also answers the following questions and more for the naturally curious reader: What is a referral? When a
dig command is issued, just what are the
ANSWER SECTIONs and
AUTHORITY SECTIONs that are returned? Why are there only 13 root-servers (because of packet size considerations)?
The chapter is laid out in two sections. The first ...