Hey all,


Wondering if anyone has any ideas on the following....

I've been playing around with my home lab and thought it would be nice to automatically add my internal DNS search suffix to windows based clients automatically on connect.

For this I have gone into the DHCP advanced options and played around with a few options. As I understand it DHCP options 119 and 135 can be used to discover suffix search orders on MacOS/*nix but are not supported by windows DHCP clients. I have an internal DNS server running from a ESXi guest running Win server 2012 and it would be nice to pass its .home suffix to some windows workstations/servers without manually setting it. I want to keep the router as the DHCP server ideally for when I bring down/break my vsphere setup. I do not run a full domain / AD currently so pushing via group policy is not an option.

After looking around I have found that DHCP option 015 could be the one I'm looking for. This should append the primary dns suffix to windows clients. However when I try to set this one the router I receive a 'The option number is reserved!' error message.

To specify the .home DNS zone I am passing the hex string '0x04 0x68 0x6f 0x6d 0x65 0x00' in the DHCP option. From what I understand the first 0x04 specify that four hex codes will follow (representing 'h' 'o' 'm' 'e') and the 0x00 ends the string.

So my questions are - 1) Is there a reason for this? 2) Can this option be modified via CLI? 3) Can I split the DHCP options for different defined networks? (IE - I don't really want to pass these options to Linux/Win servers I have setup in a DMZ on a separate VLAN/switch port).

Thanks very much! :oops:

Hi,

I had the same issue on my 2830n with firmware 3.6.4 - posting the same issue here: http://www.forum.draytek.co.uk/viewtopic.php?f=2&t=18619

I decided to rollback and have it working with firmware 3.6.3 with CLI - and it does work across both Windows and OS X/iOS devices. I haven't tried Linux, but there's no reason why it shouldn't.

This is how I get it to work telnetting to the router:

srv dhcp custom_option -e 1 -o 15 -l domainname.local

In your case, it would be:

srv dhcp custom_option -e 1 -o 15 -l home

-e 1 = enables the DHCP options
-0 15 = set DHCP Option 15
-l = Set the value "home" for the above DHCP Option

I don't know why it doesn't work with firmware 3.6.4, but that firmware was supposed to enable setting of DHCP Options via the browser and I THINK to set DHCP Options per network. Firmware 3.6.3 DHCP Options apply to all LANs that have DHCP enabled, so it will apply to your DMZ servers if that LAN has DHCP enabled as well <-- This is what I have seen, but might be different to you?

Thanks very much for your time and reply"
I shall give it a go via CLI and feed back when I get a sec.

Realise this is an old post but thought this might help others. The suggestion above didn't work on my older 2820 but I found that DHCP option 15 seems to be reserved by the WAN configuration so I added my domain suffix under:

WAN > Internet Access > WANx > Static or Dynamic IP > WAN IP Network Settings

There is a field called "Domain Name" which isn't used in my config but adding my domain suffix there passes it to DHCP clients. Maybe this works on newer models?