IT Professionals

Vista DHCP Bug Is Horrible

Posted by on Jun 6, 2008 | 8 Comments

Gnomie Zombie Ryushu writes:

I had a friend come over to my house the other day and, for the life of me, he couldn’t negotiate with my DHCP server. He was running Vista. I did some searching and found out that Vista, by default, has some bizarre flag turned on that breaks DHCP for a lot of residential routers and, more important, Linux-based DHCP servers!

To fix this issue and get Vista back to (XP’s) DHCP behavior, here are instructions. This begs the question, though: What in the world is Microsoft trying to do? Why is this flag enabled? What purpose does it serve?

I don’t think it has anything to do with Active Directory’s authoritative DHCP jails or DHCP signing. So why is this here?

  • Aaron

    Agreed, it is horrible. Made even more horrible byt he fact that the flag can’t be changed through the Network Properties, but has to be done through the registry.
    I first noticed this “feature” when Vista came out. It pretty much makes Vista unable to work with many DHCP relay, so for any business network that has multiple broadcast domains (VLANs) with less DHCP servers than broadcast domains (which is nearly any medium to large business), they may have to re-enable the broadcast flag.
    I’m suprised your Linux DHCP server doesn’t include support for the broadcast flag though, it must be in the config somewhere.

  • Wolfhard

    The question is: does this flag conform to the standard or not?
    My own experience showed that cheap routers very often don’t behave according to standards and before blaming Microsoft more investigation is needed…

  • http://brandonlive.com Brandon Paddock

    Vista is setting the flag correctly, though.

    It is also designed to auto-detect whether the router supports the flag or not, and adjust to support it.

    Details here:

    http://blogs.technet.com/teamdhcp/archive/2006/11/08/use-of-broadcast-b-flag-in-dhcp.aspx

    Did changing that key actually help your friend?

  • http://get-trax.com Joby Kent

    Vista sucks To be honest, It’s good if you put it against Linux but verses Leopard. Vista chokes.

  • Chrystoph

    Oh, come along, folks. The answer to this is obvious. They are trying to bind you to the Microsoft solution.

    “If you were using OUR servers, you wouldn’t have this problem….”

  • http://iscifi.tv Jeff Norris

    this setting is not a standard DHCP setting. Every router in the world by default blocks broadcasts, that’s the point of a router. However for DCHP to work routers use a HELPER (thought that support it) to take the DHCP broadcast from a PC or other device and forward it via unicast to the DHCP server, the resulting DHCP OFFER is sent to the router which forwards it to the client.

    lame…. vista

  • Jah Hass

    The flag didn’t fix it for me. Actually the problem is NOT on my “gaming” vista ultimate 64 desktop at home, nor the test laptop. Both of those are NOT on my corporate domain. As soon as i add ANY, and i mean any, Computer to the corporate domain. Instant problems with DHCP. i have a whole rant on tech net. The solution (for the time being – more on this in a moment) was a solution that i found that basically RESET the security of i believe network service and local service, etc… I have it if anyone wants it. BUT… an automatic update BROKE EVERYTHING AGAIN!!! WTF. this was the infamous update (that was UNINSTALLABLE) that was breaking logitech and wireless mice everywhere as well as i think soundcards. Sure system restore. turned off and disabled auto updates, and guess what. IT AUTO UPDATED AGAIN!?!!? WTF?!?!? so anyway. i blocked that update from ever happening again, but after that last update, even after the system restore… even doing the security command that fixes the registry security settings… I STILL CANT GET DHCP ADDRESSES from my vista hard drive that i now NEVER use in my laptop. sigh. i run a very basic basic windows 2003 domain and active directory setup. it has to be something, but we’ve already decided we’ll NEVER go vista, and if any of our 250 PCs start dying, we’ll just repair them. Though dell is with us until 2010. YAY dell!!!!!

  • http://vnv.phost.ws vivanv

    vista dhcp problem is a disaster to me.
    I tried to modify the registry as kb928233 told to, but everytime I beboot my computer, the first 10 seconds seemed all right but soon it will lost the connection and appeared local only,unidentified network.
    maybe it’s time to downgrade to winxp…