The ping command, built into both Windows and UNIX operating systems, is a universal way of testing network response time and performance. The ping command is used by system administrators for diagnostic problems, particularly for testing, measuring, and managing networks. Ping is a TCP/IP utility that sends ICMP information packets to a computer on a network and waits for their return. The ping command is particularly helpful in verifying whether a host is working and whether a system is attached to the Internet.

For system administrators not using Windows, several Websites offering ping are available. On UNIX or Linux, for example, the system administrator simply needs to type “ping host_name.” System administrators using a Windows-type operating system can open a command window and then type “ping host_name” (that is, the name of the host the system administrator wants to check). Figure 16-1 shows how the output will appear when someone pings the Whitehouse Webserver from a Windows machine.

See Also: Internet; Internet Control Message Protocol (ICMP); Linux; Packets; TCP/IP or Transmission Control Protocol/Internet Protocol; UNIX.