When getting problems having an IP address assigned to one Windows machine but not another one, you start to check the one that is not getting it. Thinking it’s machine specific. However, when you find that particular version of Windows doesn’t get an IP address, you start to think of the DHCP server. I was running into the following situation:
Client with CISCO router 1800 series, another router 3500 series, switch 3500 series, and a call manager with IP telephone. The 1800 router was running the DHCP for computers, on separate VLAN. For some reason all windows VISTA computers doesn’t acquire an IP address from that router.
After running a network sniffing tool, I found the request/response going just fine, so the machine should have an IP. In fact, the DHCP server already assigned that IP in the table for the MAC address and set a lease time for it. Okay, what’s wrong then? Checking the event log of VISTA found the following information:

Log Name:      System
Source:        Microsoft-Windows-Dhcp-Client
Date:          9/20/2008 5:04:40 PM
Event ID:      1001
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      MachineName
Description:
Your computer was not assigned an address from the network (by the DHCP Server) for the Network Card with network address xxxxxxxxxxxx.  The following error occurred:
The parameter is incorrect.. Your computer will continue to try and obtain an address on its own from the network address (DHCP) server.
Event Xml:
<Event xmlns=”http://schemas.microsoft.com/win/2004/08/events/event“>
  <System>
    <Provider Name=”Microsoft-Windows-Dhcp-Client” Guid=”{xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}” EventSourceName=”Dhcp” />
    <EventID Qualifiers=”0″>1001</EventID>
    <Version>0</Version>
    <Level>2</Level>
    <Task>0</Task>
    <Opcode>0</Opcode>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime=”2008-09-20T14:04:40.000Z” />
    <EventRecordID>121276</EventRecordID>
    <Correlation />
    <Execution ProcessID=”0″ ThreadID=”0″ />
    <Channel>System</Channel>
    <Computer>MachineName</Computer>
    <Security />
  </System>
  <EventData>
    <Data>xxxxxxxxxxxx</Data>
    <Data>%%87</Data>
  </EventData>
</Event>

This wasn’t clear enough, so back to the sniffing tool, I found one of the options passed along with the IP address (003 router) was passing two values, 192.168.xx.x and 255.255.255.0 and when checking the router DHCP configuration, found this:
default-router 192.168.xx.x 255.255.255.0
My guess that the CISCO guy who configured this missed the command syntax thinking he/she should add a subnet mask to it, which for some reason doesn’t affect any OS except the VISTA!!!
I tried my Linux version, and other XP systems in the office and all were running just fine with that ignoring the bad parameter!