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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols

Internet Relay Chat Protocol (IRC) 1 TCP/IP Host Name Utility (hostname)

The first two large subsections of the large section devoted to TCP/IP applications and application protocols discussed file and message transfer applications, and interactive and remote access applications, respectively. These are the classical applications that are most often employed by the users of TCP/IP internetworks. Since they are the means by which users communicate, they can be considered in some ways the “raison d’être” of TCP/IP and the Internet itself.

In contrast, this third subsection is a bit different. It doesn’t describe applications designed for end-users. Rather, it discusses a set of TCP/IP troubleshooting utilities and protocols, which are normally the province of internetwork administrators. Even though millions of people use TCP/IP every day without even knowing that these applications exist—much less how they work—they are critically important to those who maintain TCP/IP internetworks. Since many of you are studying TCP/IP so that you can implement and administer this technology, understanding how these applications work is well worth your time.

In this section I provide an overview description of a number of software utilities that are commonly employed to help set up, configure and maintain TCP/IP internetworks. These programs allow a network administrator to perform functions such as checking the identity of a host; verifying connectivity between two hosts; checking the path of routers between devices; examining the configuration of a computer; looking up a DNS domain name; and much more.

Internet Relay Chat Protocol (IRC) 1 TCP/IP Host Name Utility (hostname)