Identify the TCP/IP Configuration by Using IPConfig

When troubleshooting a TCP/IP networking problem, begin by checking the TCP/IP configuration on the computer experiencing the problem. Use the ipconfig command to get the host computer configuration information, including the IP address, subnet mask, and default gateway. Ipconfig is a command-line utility that prints out the TCP/IP-related configuration of the local computer.

Note

Windows 95 users use winipcfg in place of ipconfig.

When ipconfig is used with the /all switch, it produces a detailed configuration report for all interfaces, including any configured serial ports (RAS). Ipconfig output may be redirected to a file and pasted into other documents. This output of ipconfig can be reviewed to find any problems in the computer network configuration. For example, if the computer has been configured with an IP address that is a duplicate of an existing IP address, the subnet mask will appear as 0.0.0.0.

The following example illustrates the results of an ipconfig/all command on a computer that is configured to use a DHCP server for automatic TCP/IP configuration, and WINS and DNS servers for name resolution:


Windows NT IP Configuration Host Name . . . . . . . . . : davemac1.terraflora.com DNS Servers . . . . . . . . : 172.16.48.03 Node Type . . . . . . . . . : Hybrid NetBIOS Scope ID. . . . . . : IP Routing Enabled. . . . . : No WINS Proxy Enabled. . . . . : No NetBIOS Resolution Uses DNS : No Ethernet adapter Elnk31: Description . . . . . . . . : ELNK3 Ethernet Adapter. Physical Address. . . . . . : 00-20-AF-1D-2B-91 DHCP Enabled. . . . . . . . : Yes IP Address. . . . . . . . . : 172.16.48.10 Subnet Mask . . . . . . . . : 255.255.248.0 Default Gateway . . . . . . : 172.16.48.03 DHCP Server . . . . . . . . : 172.16.48.03 Primary WINS Server . . . . : 172.16.48.03 Secondary WINS Server . . . : 172.16.48.03 Lease Obtained. . . . . . . : Sunday, June 25, 1996 11:43:01 PM Lease Expires . . . . . . . : Wednesday, June 28, 1996 11:43:01 PM Ethernet adapter NdisWan5: Description . . . . . . . . : Physical Address. . . . . . : 00-00-00-00-00-00 DHCP Enabled. . . . . . . . : No IP Address. . . . . . . . . : 0.0.0.0 Subnet Mask . . . . . . . . : 0.0.0.0 Default Gateway . . . . . . :

If no problems appear in the TCP/IP configuration, the next step is to test the ability to connect to other host computers on the TCP/IP network.