Troubleshooting Connectivity

For anyone working with TCP/IP networks, troubleshooting connectivity is something that is simply going to have to be done. This tutorial identifies the tools that are used in the troubleshooting process and identifies scenarios in which these tools can be used.

Troubleshooting with Diagnostic Utilities

Many utilities can be used when troubleshooting TCP/IP. Although the actual utilities available vary from platform to platform, the functionality between platforms is quite similar. Table 1 lists the TCP/IP troubleshooting tools along with their purpose.

Common TCP/IP Troubleshooting Tools and Their Purpose

tracert / traceroute: Used to track the path a packet takes as it travels across a network. tracert is used on Windows systems, traceroute is used on UNIX, Linux, and Macintosh systems.

ping: Used to test connectivity between two devices on a network.

arp: Used to view and work with the IP address to MAC address resolution cache.

netstat: Used to view the current TCP/IP connections on a system.

nbtstat: Used to view statistics related to NetBIOS name resolutions, and to see information about current NetBIOS over TCP/IP connections.

ipconfig: Used to view and renew TCP/IP configuration on a Windows system.

ifconfig: Used to view TCP/IP configuration on a UNIX, Linux or Macintosh system.

winipcfg: Graphical tool used to view TCP/IP configuration on Windows 95, 98, and Me.

nslookup / dig: Used to perform manual DNS lookups. nslookup can be used on Windows, UNIX, Macintosh, and Linux systems. dig can only be used on UNIX, Linux, and Macintosh systems.

The following sections look in more detail at these utilities and the output they produce.