IPConfig is a command-line tool that displays the current configuration of the installed IP stack on a networked computer.
What does that mean? Basically it is going to display information about your computer and how it interacts with a local network or the internet.
There are several switches you can use with IPConfig.
| /all | Produces a detailed configuration report for all interfaces. |
| /flushdns | Removes all entries from the DNS name cache. |
| /registerdns | Refreshes all DHCP leases and re-registers DNS names. |
| /displaydns | Displays the contents of the DNS resolver cache. |
| /release < adapter > | Releases the IP address for a specified interface. |
| /renew < adapter > | Renews the IP address for a specified interface. |
| /? | Displays a help file that contains this list. |
There are also two more we will not cover here.
To run IPConfig, click
Start -> All Programs -> Accessories ->
Command Prompt. Now type in
ipconfig and press
Enter. Below is what you will see. If you are using Windows XP then the entries marked Tunnel adapter will not be seen.
IPCONFIG
Windows IP Configuration
Wireless LAN adapter Wireless Network Connection:
Connection-specific DNS Suffix . :
Link-local IPv6 Address . . . . . : xxxx::xxxx:xxxx:xxxx:xxxx
IPv4 Address. . . . . . . . . . . : 192.168.1.102
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1
Ethernet adapter Local Area Connection:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Tunnel adapter Local Area Connection* 6:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Tunnel adapter Local Area Connection* 7:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Tunnel adapter Local Area Connection* 9:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Below is what you will see if you use the /all switch (ipconfig /all)
Windows IP Configuration
Host Name . . . . . . . . . . . . : Name of the Computer
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
Wireless LAN adapter Wireless Network Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Dell Wireless 1505 Draft 802.11n WLAN Mini-Card
Physical Address. . . . . . . . . : 00-00-00-00-00-00
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : xxxx::xxxx:xxxx:xxxx:xxxx(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.1.102(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Monday, November 29, 2010 13:33:38
Lease Expires . . . . . . . . . . : Monday, December 06, 2010 12:12:39
Default Gateway . . . . . . . . . : 192.168.1.1
DHCP Server . . . . . . . . . . . : 192.168.1.1
DHCPv6 IAID . . . . . . . . . . . : 000000000
DHCPv6 Client DUID. . . . . . . . : 00-00-00-00-00-00-00-00-00-00-00-00-00-00
DNS Servers . . . . . . . . . . . : 24.247.24.53
24.247.15.53
156.154.70.1
NetBIOS over Tcpip. . . . . . . . : Enabled
Ethernet adapter Local Area Connection:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Broadcom 440x 10/100 Integrated Controller
Physical Address. . . . . . . . . : 00-00-00-00-00-00
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Tunnel adapter Local Area Connection* 6:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : isatap.{00000000-0000-0000-0000-000000000000}
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-00
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Tunnel adapter Local Area Connection* 7:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : isatap.{00000000-0000-0000-0000-000000000000}
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-00
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
Tunnel adapter Local Area Connection* 9:
Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Physical Address. . . . . . . . . : 00-00-00-00-00-00
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
In the above logs there are a few things you will need to know how to find and what they are.
IPv4 address is the IP address of your computer using the v4 method of addressing. For now this is the address that most of the internet is using, but the changeover to v6 is progressing.
Subnet Mask is a number used in combination with the IP address to determine the range of addresses available to the network.
Default Gateway is the IP address where your internet access actually comes from. With a router, you will be getting your access from your modem, so this will be the IP address of the modem. But in your modem, there will be another default gateway address that will either be another router, a server, or a wireless radio.
Media state is for IPv6 only. This may come in handy if you are connected via IPv6, it will tell you if the connection is enabled or disabled. You can then compare what it says, with what you think it is suppose to say.
Host name is the name of the computer.
Description describes about the device that is handling the IPv4 connection.
Physical Address is also known as the MAC address
DHCP Enabled, that means that the IP address of the device may change. In home networks the actual IP Address may stay the same, but if you check the lease on the IP address, it will keep updating when it expires.
Autoconfiguration enabled, means the device is able to access another device to get IP address’s and DNS address’s to use.
Lease obtained and lease expired have to do with your IP address. This “lease” is basically the time remaining before the IP address currently assigned to your computer expires and must then be renewed. Once the lease has expired, the computer has to get a new IP address with a new lease. On small networks, chances are you will keep the same IP address but the lease will expire and have to be renewed. This is all done automatically.
DHCP Server is where your computer goes to get its IP address and the lease for that address.
DNS Servers are where your computer goes to lookup the IP address that corresponds to a web address.
NetBIOS over TCP/IP can be thought of as the way your computer tells all the other devices on the network its name.
Most of the other entries have to do with IPv6 and are not really implemented yet, so they will be left out until such time as they start becoming more common.
The /flushdns switch (used like this:
ipconfig /flushdns) is used to flush the DNS cache in your computer. If you are having difficulty accessing sites, you may need to flush the DNS cache using this command, or another method, to make sure that your computer is looking up the correct IP address.
The /registerdns switch relates to the DHCP leases on your local network. If your network is having a communication problem, running this command may solve it.
The /displaydns displays the contents of the DNS resolver cache. Chances are you will not use this.
And finally there are the /release and /renew switches. These will force your computer to release the IP address and then ask for a new one.
Ipconfig does not display much information, but if you get familiar with the information it does show, it will help in troubleshooting many networking problems.
