Chapter 7

TCP/IP Tools and Commands

IN THIS CHAPTER

Bullet Recognizing tools and commands

Bullet Making all your hosts sing with IPConfig and Ping

Most client and server operating systems that support Transmission Control Protocol/Internet Protocol (TCP/IP) come with a suite of commands and tools that are designed to let you examine TCP/IP configuration information and diagnose and correct problems. Although the exact form of these commands varies between Windows and Unix/Linux, most are surprisingly similar. This chapter is a reference to the most commonly used TCP/IP commands.

Using the arp Command

Using the arp command allows you to display and modify the Address Resolution Protocol (ARP) cache, which is a simple mapping of IP addresses to MAC addresses. Each time a computer's TCP/IP stack uses ARP to determine the Media Access Control (MAC) address for an IP address, it records the mapping in the ARP cache so that future ARP lookups go faster.

If you use the arp command without any parameters, you get a list of the command's parameters. To display the ARP cache entry for a specific IP address, use an -a switch followed by the IP address. For example:

C:\>arp -a 192.168.168.22Interface: 192.168.168.21 --- 0x10004Internet Address Physical Address Type192.168.168.22 00-60-08-39-e5-a1 ...

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