Alternate Configuration


You don't have to settle for the APIPA address just because you're a DHCP client and you can't reach a DHCP server. In fact, this behavior is only so because of XP's default settings.

Notice that when you choose the radio button "Obtain an IP address automatically," you have another tab on the TCP/IP Properties dialog box. It's called "Alternate Configuration," and from this tab you can manually set a preconfigured IP configuration in the event that a DHCP server cannot be located. This can be a very good idea if you're working in a network where there are lots of manually configured computers that you must reach no matter what.

For example, say your network includes mail and database servers that have manually configured IP addresses in the 192.168.10.x range. Now the DHCP server is down, and APIPA assigns your system a 169.254.x.y IP address. Can you connect to the mail and database servers? No, because to your APIPA computer, they appear on a different network.

But, if you set up an Alternate Configuration with user-defined settings, such as 192.168.10.200, you should be good to go (assuming you get the subnet mask correct). Why? Because you're still on the same network. Your mail and database information will continue to flow uninterrupted.

And because you can set up a default gateway, this can be a way to ensure that Internet connectivity remains uninterrupted, even when DHCP connectivity is interrupted.

Here's how you set up the user-defined IP configuration, effectively disabling APIPA:

1.

Open the Network Connections Control Panel applet. Select the network connection you wish to configure, right-click, and choose Properties.

2.

From the General tab of the connection's Properties dialog box, choose the Internet Protocol (TCP/IP) and then click Properties.

3.

From the General tab of the TCP/IP Properties dialog box, click the "Obtain an IP address automatically" option.

4.

On the Alternate Configuration tab, click the "User configured" option, and then type in the values for IP address, subnet mask, default gateway, and DNS server, as shown in Figure 9-5.

Figure 9-5. Setting up an alternate configuration.


This can also be very helpful on laptops, which can move between a home office, where DHCP is used, to a corporate network, where administrators have set up all clients with manual IP address settings.



Spring Into Windows XP Service Pack 2
Spring Into Windows XP Service Pack 2
ISBN: 013167983X
EAN: 2147483647
Year: 2004
Pages: 275
Authors: Brian Culp

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