Enabling DHCP Option 119 on 2003 Server

DHCP option 119 is the option to send out DHCP domain search list to clients, it is documented in RFC 3397.

It is only supported in Macintosh, Windows XP and older does not support it and as far as I know neither does Vista. You must use GPO for Windows.

In your Windows DHCP server do the following

  1. Go to “Set Predefined Options”
  2. Click Add
  3. Name: Domain Search List
  4. Data Type : Byte, Check Array
  5. Code: 119

To create your byte array go to http://www.string-functions.com/string-hex.aspx and type in your domain. We will use apple.com as our example.

We are returned get back this: 6170706c652e636f6d

To enter them in to DNS we have to add 0x in front of each pair. Which gives us 0x61 0x70 0x70 0x6c 0x65 0x2e 0x63 0x6f 0x6d (A)

Add up all the groups which is 9 in our example and convert that to hex which is 0x9 (B).

Now, in Windows DHCP you have to enter value one at a time into DNS. When you enter your first value MS adds a 0x0 which you have to remove first.

Then add all the values from (A) first the (B) and you are all set.

10 thoughts on “Enabling DHCP Option 119 on 2003 Server”

  1. Stephen,

    Could add a little more detail to your instructions for adding domains to option 119?

    I am particularly confused by the last statement,
    "(B). Now, in Windows DHCP you have to enter value one at a time into DNS. When you enter your first value MS adds a 0x0 which you have to remove first. Then add all the values from (A) first the (B) and you are all set."

    – What values am I entering into DNS, and where?
    – So when I am done adding entries into the New Value field in DHCP for option 119, I should have a long list of 4 characters with the last last one in the list being say… 0x9 from your example above?

    Thank you,

    -Ted

    Reply

    1. *scratches head* The rfc you referred to, says to use exactly what chankster is pointing to. someone didn’t pay attention

      Reply

  5. Thanks for the info. I haven’t tried this yet, but from http://technet.microsoft.com/en-us/library/dd572752(office.13).aspx, it looks much easier to do. Per that MS article, you can enter your suffixes as regular character strings. Why did you have to enter yours as hex strings? This is from the MS article: To enable search option 119 for Windows Server 2003 DHCP server. . . Enter a list of domain suffixes in your organization, delimited by a semicolon (for example, contoso.com;dev.contoso.com;corp.microsoft.com).

    Reply

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