Domain Name System - Wikipedia
https://en.wikipedia.org/wiki/Domain_Name_System
The DNS protocol uses two types of DNS messages, queries and replies; both have the same format. Each message consists of a header and four sections: question, answer, authority, and an additional space. A header field (flags) controls the content of these four sections. The header section consists of the following fields: Identification, Flags, Number of questions, Number of answers, Number of authority resource records (RRs), and Number of additional RR…
DA: 21 PA: 39 MOZ Rank: 50