Understanding DNS

The DNS concept dates back to the 1960s, also known as the ARPANET era. At that time, scientists engaged in the ARPANET project were trying to find a way of memorizing names instead of IP addresses. Decades later, at the beginning of the 1980s, the first specification documents were published about DNS in Requests for Comments (RFC) documents.

DNS has a tree structure (hierarchical), where each branch represents the root zone, and each leaf has zero or more resource records. Each zone can represent a root domain or multiple domains and sub-domains. A domain name consists of one or more components, known as labels, and is separated by a period; for example, packtpub.com. DNS is maintained by a database that uses a distributed clients/server architecture where network hosts represent the servers’ names. Thus, the following steps illustrate how DNS works:

1. If you enter www.packtpub.com in your browser’s address bar and press Enter, your computer...