Introduction

When internetworking was first conceived and implemented in the 1960s and 1970s, the Internet Protocol (IP) addressing scheme was also devised. It uses four sets of 8 bits (octets) to identify a unique address, which is composed of a network address and a unique host address. This provided enormous flexibility because this scheme allowed for millions of addresses. The original inventors of this system probably didn t envision the networking world as it is today with millions of computers spanning the globe, many connected to one worldwide network, the Internet.

IP addressing works quite well, but most people have trouble remembering up to 12 digits at a time. If a friend says, Yeah, just e-mail me, my e-mail address is me@247.84.132.167, you ll probably forget it, or transpose one or more numbers. If your friend says Yeah, just e-mail me, my e-mail address is me@myname.com, you ll likely remember it. Similarly, it s easier to send a print job to a printer named HRLaserPrt1 rather than 154.39.187.241. Human brains can work well with numbers, but in terms of memory, we re more likely to remember a name than a long number. Computers, on the other hand, can only process binary information numbers. As a result, computers connected to networks have both IP addresses and computer names. These names are sometimes referred to as computer names or host names.

In this chapter, we explore the Domain Name System (DNS). This is a method of creating hierarchical names that can be resolved to IP addresses...