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.