Don's Home Technology PC - Windows Reference XP Service Pack 2 Contact
Win9x:
Go to Start | Run, enter WINIPCFG ;
Select the Network Card from the Drop-Down menu;
Click 'More Info';
Click 'Release';
Click 'Renew';
Observe the following parameters which should have been obtained:
IP Address: 192.168.0.x ( 'x' probably =2 )
Subnet Mask: 255.255.255.0
Default
Gateway: 192.168.0.1
DHCP Server: 192.168.0.1
DNS Servers: As per router's DHCP page, eg:
192.168.0.1 and 213.120.62.100

Windows 2000 / XP:
There is no winipcfg in Windows 2000 / XP.
Go to a command prompt and issue the commands:
ipconfig /release
ipconfig /renew
ipconfig /all
The final command will display all the current IP configuration.
Observe the following parameters which should have been obtained:
IP Address: 192.168.0.x ( 'x' probably =2 )
Subnet Mask: 255.255.255.0
Default
Gateway: 192.168.0.1
DHCP Server: 192.168.0.1
DNS Servers: As per router's DHCP page, eg:
192.168.0.1 and 213.120.62.100
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If you are running Windows 95 or 98:
Click on the following tabs and write down the settings you find. Right-click on Network Neighborhood and select Properties. Select "TCP/IP" for your network adapter. Then click Properties. 
1.	Click the IP Address tab and select "Obtain an IP address automatically." 
2.	Click the Gateway tab. If there are any "Installed gateways," highlight them and click Remove. 
3.	Click the DNS tab and select "Disable DNS." 
4.	Click OK

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If you are running Windows NT:
Write down any settings you see throughout the tabs for future reference. Right-click on Network Neighborhood and select Properties. Click the Protocols tab, highlight TCP/IP, then click on Properties. Click the IP Address tab and select "Obtain an IP address automatically." Remove any gateway settings you see. Click OK. 

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If you are running Windows 2000:
Right-click on My Network Places. Click on Properties. Double-click on the Local Area Connection icon that connects to the Router. Click on the Properties button. Highlight TCP/IP, then select "Obtain an IP address automatically." Click OK.



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http://www.winnetmag.com/Articles/Index.cfm?ArticleID=746

AutoNet, Auto-IP Configuration, IP-Auto Configuration, and Automatic Private IP Addressing. In Win2K Release Candidate 2 (RC2), Microsoft has settled on Automatic Private IP Addressing (APIPA).

With APIPA, DHCP clients can automatically self-configure an IP address and subnet mask when a DHCP server isn't available. You don't need to do anything special on the clients to enable this feature. Just make sure that you configure your Win2K clients to obtain IP information from a DHCP server, as Screen 1 shows. You do this by selecting "Obtain an IP address automatically" on the General tab of the TCP/IP properties dialog box for your network adapter. By default, all Win2K clients are configured for DHCP. APIPA also works on Windows 98 clients by default.

How APIPA Works 
When a DHCP client boots up, it looks for a DHCP server to obtain an IP address, subnet mask, and other possible DHCP options configured on the server. If the client is unable to obtain a lease from a DHCP server, the client uses APIPA and automatically configures itself with an IP address from the Microsoft-reserved IP address range of 169.254.0.1 through 169.254.255.254. The Internet Assigned Numbers Authority (IANA) has reserved this range for private IP addressing, so no one can use it on the Internet. The client also configures itself with a default class B subnet mask of 255.255.0.0. A client uses the self-configured IP address until a DHCP server becomes available. Obviously, APIPA is meant for nonrouted small business environments.
last updated 26 Dec 2002