# Wireless networking on vista doesn't get a valid DHCP IP

When trying to connect to the <span class="caps">UCLAWLAN</span>, the IP obtained would be 169.254.×.×. This is sign that the machine cannot reach the <span class="caps">DHCP</span> server.

From Microsoft’s knowledgebase article on this.  
Consider the following scenario:  
• You connect a Windows Vista-based computer to a network.  
• A router or other device that is configured as a Dynamic Host Configuration Protocol (<span class="caps">DHCP</span>) server is configured on the network.  
• The router or the other device does not support the <span class="caps">DHCP</span> <span class="caps">BROADCAST</span> flag.  
In this scenario, Windows Vista cannot obtain an IP address.

Cause:  
This issue occurs because of a difference in design between Windows Vista and Microsoft Windows XP Service Pack 2 (SP2). Specifically, in Windows XP SP2, the <span class="caps">BROADCAST</span> flag in <span class="caps">DHCP</span> discovery packets is set to 0 (disabled). In Windows Vista, the <span class="caps">BROADCAST</span> flag in <span class="caps">DHCP</span> discovery packets is not disabled. Therefore, some routers and some non-Microsoft <span class="caps">DHCP</span> servers cannot process the <span class="caps">DHCP</span> discovery packets.

See Microsoft’s knowledgebase article for the solution:  
[http://support.microsoft.com/kb/928233/EN-US/](http://support.microsoft.com/kb/928233/EN-US/)