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How to request domain-search option from DHCP server ?

    Question

  • We have an ISC DHCP server which supports the "domain-search" option per RFC3397.

    On Linux clients, if they are configured to request that parameter, they can automatically set multiple DNS search domains, e.g. "uk.example.com us.example.com". (They can also accept multiple domains  from "domain-name", which Windows won't, probably because it's illegal usage). The Linux clients can also request other options, like "www-server".

    I wondered if there was a way in Windows (XP, 7) to request extra, or substitute, DHCP options, and if "domain-search" was succesfully reuqested, whether the system would make use of it.

    Tuesday, January 25, 2011 10:24 PM

Answers

  • I don't believe it's supported, because the DHCP server will only give an option if the option was requested by the DHCP client. So it appears that would need additional configuration on the client side such as the option. Here's more at this thread:

    DHCP Option 119 does not exist in WS2008...?
    http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/c47a8c9c-4a5f-4722-878a-142c0a6f7281

    More info:

    DHCP option 119 from a Windows 2008 DHCP server Options
    http://groups.google.com/group/macenterprise/browse_thread/thread/a2c866474c75d727

    Cisco - DHCP Attribute 119 (with instructions for Windows 2003 DHCP)
    http://www.velocityreviews.com/forums/t42351-dhcp-attribute-119-a.html

    Enabling DHCP Option 119 on 2003 Server
    http://www.stephenjc.com/2009/04/07/enabling-dhcp-option-119-on-2003-server/

    Convert String to hex
    http://www.string-functions.com/string-hex.aspx

    How to Configure DHCP Class ID on a Windows 2000 DHCP ClientFeb 27, 2007 ... For SetClassID, if no class id is specified, then the classid is removed. Examples: > ipconfig ... Show information. > ipconfig /all . ...
    http://support.microsoft.com/kb/235272


    To set Options on client side:

    Show DHCP class ID information at a client computer: Dynamic Host ...Jan 21, 2005 ... Use the Ipconfig command-line utility to show the DHCP class ID that the client ... command as demonstrated in the following example command. ... For a DHCP options class to be in effect between the DHCP server and its ...
    http://technet.microsoft.com/en-us/library/cc758890(WS.10).aspx

    How to Create a New DHCP User or Vendor ClassMar 1, 2007 ... These option classes are vendor-defined and user-defined ...
    http://support.microsoft.com/kb/240247

     

    If the DHCP clients are all Windows, you can use a GPO to configure DNS Search suffixes:

    ==================================================================
    Using GPOs to configure DNS Search Suffixes

    At this time Win2k3 DHCP cannot assign a DNS suffix search list. That said,
    you can assign a connection specific DNS suffix (option 015), which is added
    to the search list. But, you can assign only one DNS suffix per client.

    There is a GPO that assigns a custom DNS suffix search list to XP and Win2k3
    clients which can be assigned by Win2k DCs if you upgrade the GPOs using a
    Win2k3 or XP client.

    Upgrading Windows 2000 Group Policy for Windows XP:
    http://support.microsoft.com/default.aspx?scid=kb;en-us;307900

    After the GPOs have been upgraded, expand the Group policy to here to apply
    the custom search list.
    Computer Configuration
       -Administrative templates
             -Network
                   -DNS Client

    Also...

    If you want to kill the devolution tickbox, have a look at this article:
    http://www.insidetheregistry.com/regdatabase/viewvalue.asp?valueid=320

    It refers to the registry key controlled by GPO - this will over-ride the standard internal registry setting at:
    HKLM\System\CurrentControlSet\Services\TCPIP\Parameters\UseDomainNameDevolution

    You could also use populate the regkey by script if you didn't want to pull in the extra ADMX GPO template... and this will force your client to JUST resolve hosts on internal.domain.com or whatever:

    ---
    Windows Registry Editor Version 5.00

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters]
    "SearchList"="domain1.com,domain2.com"

    ---
    Or use the command:
    reg add HKLM\system\currentcontrolset\services\tcpip\parameters /v "SearchList" /d "domain1.com,domain2.com" /f
    ---

    The key thing to observe with manual suffix lists, (from KB275553, link below), is that if you distribute a suffix list then it blocks devolution and use of
    primary or connection-specific suffixes... so write that list carefully !

    How to configure a domain suffix search list on the Domain Name System clients
    http://support.microsoft.com/?id=275553
    ==================================================================

    Ace


    Ace Fekay
    MVP, MCT, MCITP EA, MCTS Windows 2008 & Exchange 2007, MCSE & MCSA 2003/2000, MCSA Messaging 2003
    Microsoft Certified Trainer
    Microsoft MVP - Directory Services

    This posting is provided AS-IS with no warranties or guarantees and confers no rights.

    Wednesday, January 26, 2011 6:16 AM