W2k8 - DHCP option 252 problem

Discussion in 'Server Networking' started by Radovan Vojtek, Apr 29, 2008.

  1. Hi all,

    I've defined 252 DHCP option (DHCP) on our W2k8 DHCP server for autoconfig
    proxy. However, it doesn't work.

    In NetMon I've noticed that DHCP server DOES NOT send this option in DHCP
    OFFER.

    Isn't there some policy in W2k8 that could block the 252 option?

    Thanks,
     
    Radovan Vojtek, Apr 29, 2008
    #1
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  2. I combine it with DNS. Not everything is going to be able to use the DHCP
    method. You need it to work by both DNS and DHCP, and the two have to work
    together.

    First:
    Create a CNAME entry in DNS called "wpad". Point it at the Host Record for
    the Proxy Server.

    Second:
    Create the DHCP Option and point it at the DNS CNAME like this,
    http://wpad.mydomain.loc

    Third:
    Configure the Proxy to "publish" its autoconfiguration script on port 80.
    It *must* be port 80 or the DNS wpad setup will fail.
    Open a web browser and go to the link http://wpad.mydomain.loc/wpad.dat
    You should be prompted to Save or Open. Choose Open and you will see the
    contents of the auto-configuration script.

    http://www.google.com/search?hl=en&...=&as_occt=any&cr=&as_nlo=&as_nhi=&safe=images

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
     
    Phillip Windell, Apr 29, 2008
    #2
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  3. Hello Philip,

    thanks for your reply!

    I cannot publish the wpad.dat on port 80 and I cannot use the the default
    one from ISA - so that I modify the default one and create website on the
    port 888. On the DHCP server I created 252 option for WPAD with
    "http://1.2.3.4:888/wpad.dat" value accordint to the following technet
    articles:

    http://www.microsoft.com/technet/isa/2004/help/FW_AutoDiscIntro.mspx?mfr=true
    http://www.microsoft.com/technet/isa/2004/help/CMT_H_CnfDHCP.mspx?mfr=true
    http://www.microsoft.com/technet/isa/2004/help/SRSP1_H_Create252.mspx?mfr=true

    I cannot use the DNS-based publishing of the wpad.dat. I need it for the
    quarantine VLAN where are only non-domain computers with external DNS servers
    defined (via DHCP) - so that there is no way to define wpad DNS entry with
    the internal IP.

    So my question is - how to force the W2k8 DHCP server to send the 252 option
    in DHCP OFFER packets?
     
    Radovan Vojtek, Apr 29, 2008
    #3
  4. What happens when you use http://1.2.3.4:888/wpad.dat in a browser address
    bar?


    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------
     
    Phillip Windell, Apr 29, 2008
    #4
  5. Hi Phillip,
    I can access and download the wpad.dat file. It works fine in my test lab on
    the W2k3 DHCP server - the 252 option is sent to the clients and use for
    proxy autodiscovery. However in the production with W2k8 DHCP server it
    doen's work as far as the 252 option is not send to the clients...
     
    Radovan Vojtek, Apr 30, 2008
    #5
  6. I don't know then,...I don't use 2008

    --
    Phillip Windell
    www.wandtv.com

    The views expressed, are my own and not those of my employer, or Microsoft,
    or anyone else associated with me, including my cats.
    -----------------------------------------------------
     
    Phillip Windell, Apr 30, 2008
    #6
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