Network Administration: The ipconfig Command

Using the ipconfig command displays information about a computer’s TCP/IP configuration. It can also be used to update DHCP and Domain Name Server (DNS) settings.

Displaying basic IP configuration

To display the basic IP configuration for a computer, use the ipconfig command without any parameters, like this:

C:>ipconfig
Windows IP Configuration
Ethernet adapter Local Area Connection:
   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::cca:9067:9427:a911%8
   IPv4 Address. . . . . . . . . . . : 192.168.1.110
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.1.1
Tunnel adapter Local Area Connection* 6:
   Connection-specific DNS Suffix  . :
   IPv6 Address. . . . . . . . . . . : 2001:0:4136:e38c:2c6c:670:3f57:fe91
   Link-local IPv6 Address . . . . . : fe80::2c6c:670:3f57:fe91%9
   Default Gateway . . . . . . . . . : ::
Tunnel adapter Local Area Connection* 7:
   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::5efe:192.168.1.110%10
   Default Gateway . . . . . . . . . :
C:>

When you use ipconfig without parameters, the command displays the name of the adapter, the domain name used for the adapter, the IP address, the subnet mask, and the default gateway configuration for the adapter. This is the easiest way to determine a computer’s IP address.

If your computer indicates an IP address in the 169.254.x.x block, odds are good that the DHCP server isn’t working. 169.254.x.x is the Class B address block that Windows uses when it resorts to IP Autoconfiguration. This usually happens only when the DHCP server can’t be reached or isn’t working.

Displaying detailed configuration information

You can display detailed IP configuration information by using an /all switch with the ipconfig command, like this:

C:>ipconfig /all
Windows IP Configuration
   Host Name . . . . . . . . . . . . : WK07-001
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection:
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Intel(R) PRO/100 VE Network Connection
   Physical Address. . . . . . . . . : 00-12-3F-A7-17-BA
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::cca:9067:9427:a911%8(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.1.110(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.1.1
   DNS Servers . . . . . . . . . . . : 192.168.1.10
                                       68.87.76.178
   NetBIOS over Tcpip. . . . . . . . : Enabled
C:>

You can determine a lot of information about the computer from the ipconfig /all command. For example:

• The computer’s host name is WK07-001.

• The computer’s IPv4 address is 192.168.1.110, and the subnet mask is 255.255.255.0.

• The default gateway is a router located at 192.168.1.1.

• This router is also the network’s DHCP server.

• The DNS servers are at 192.168.1.10 and 68.87.76.178.