CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

3.4. Troubleshooting with TCP/IP Utilities

After you have TCP/IP installed and configured and you have your TCP/IP network running, you need to be able to troubleshoot the network. When problems arise on a Windows network, you can use some of the following commands to do your troubleshooting:

• IPCONFIG

• PING

• TRACERT

• NBTSTAT

• NETSTAT

• PATHPING

• NSLOOKUP

The following sections discuss these popular TCP/IP utilities that are used to troubleshoot TCP/IP connectivity.

3.4.1. IPCONFIG

On Windows systems, you can run the ipconfig (IP configuration) utility, which shows you the current TCP/IP configuration of the Windows desktop, such as the IP address, subnet mask, and default gateway. If the computer is a DHCP client, ipconfig identifies the server that has given the IP address and also shows how long the IP address will be used by the client. Table 3-3 shows some of the switches supported by the utility ipconfig.exe.

Table 3.3. IPCONFIG Switches

Switch	Description
/?	Shows a list of switches supported by ipconfig.exe and a brief description of each switch
/all	Shows all TCP/IP information — for example, DHCP lease period and the DNS server
/release	Releases the current IP address information assigned by the DHCP server
/renew	Requests new IP address information from the DHCP server
/displaydns	Displays the DNS resolver cache which stores recent results from DNS queries
/flushdns	Clears the DNS resolver cache

For example, to use the ipconfig utility and view just the basic TCP/IP settings, you type the following ...