DNS is a remarkably complex system—one that many fine books are entirely dedicated to explaining. I won't try to explain the intricacy and nuance of the system's operational mechanics in a single chapter. My intent is to simply provide you with an overview of the system as it relates to Internet names and numeric addresses.
The basic concept of DNS was spelled out in RFCs 882 and 883, which were published in November 1983. Numerous updates have been made to this basic description (including RFCs 1034 and 1035) in the nearly 20 years since they were published, but the core of DNS has remained. At its simplest, DNS is a hierarchical, distributed database. The two key aspects of DNS are