Windows XP - Former classID sent

Nicolas Ecarnot nicolas at
Tue May 3 10:38:42 UTC 2011

Hi list,

This is not a question, but a report.

By a VB script copied locally then ran, I'm modifying a thousand of 
windows XP hosts from a static setup to a dhcp one with classIDs.
Some hosts were already using dhcp and an old classID, but changed to a 
new classID.

Along the use of this script, I realize that on some seldom hosts, 
changing their classID did worked (ipconfig /all does show the correct 
new classID), but a tcpdump on the DHCP server show that what is 
received is the *former* classID!

Launching a cmd then ipconfig /release then renew does not improve this 
Rebooting the windows hosts does not improve this behaviour!!!

Checking the windows host registry shows the correct new classID.

The only way to cope with it is to re-run ipconfig /setclassid blahblah 
via the cmd.exe's host itself, then use windows'GUI explorer.exe and the 
"Repair interface" right click way.

Would I have observed that once, I would have taken a rest, two coffees 
and blame myself.
Las, I observed that 4 or 5 times, witnessed by an expert co-worker.


Nicolas Ecarnot

More information about the dhcp-users mailing list