W2K8 R2, DHCP and VLAN


I'm trying to get my head around what I need to do to implement 2 VLANs (for starters) on my network.

I'm running my domain controller (providing DHCP services) on a Hyper-V VM. The server has one physical network card.

This is connected to a Linksys Cisco SLM248G switch.

My DHCP server currently servers out a single scope ( to with a subnet mask of

I want to add a VLAN and have DHCP serve out addresses to Machines on this VLAN will need to be able to access the DC and file services on the DC (it has a static IP of The machines requiring these addresses are wireless and are connected via a Netgear WNDAP350 access point.

Where do I start? I know I need to configure my switch and add the IP-helper-address, but I dont understand how Windows knows which scope to serve out addresses from.

I get the feeling my question is incomplete. Sorry.


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Krzysztof PytkoConnect With a Mentor Senior Active Directory EngineerCommented:
Yes, but it requires a lot of administrative effort :(
In DNS section make sure that you set up internal DNS only! ISP or any openDNS addresses should be configured on DNS server in Forwarders section.

Besides a lot of administrative work it will work.

Krzysztof PytkoSenior Active Directory EngineerCommented:
It will evaluate from DHCP Relay Agent/IPHelper request and then issues appropriate IP from scope. Just configure all scopes with correct settings (mostly

003 Default Gateway (router)
006 internal DNS servers
015 DNS domain name (FQDN)


and that's all :)

I'm not sure if that switch supports layer 3 routing or not, you'll need to check.  If not, your router will need to be set up to route between the VLANs.  Then, like the other guy said, you would configure a DCHP helper address on the router (or switch) interfaces to point to the address of your DCHP sever, since DHCP requests are broadcast and normally not routed.

interface <interface name, this is the default gateway for the VLAN>
  ip helper-address <IP address of DHCP server>

The server will automaticlly hand out address to the correct subnet as long as the proper scope in configured.
jeffeldAuthor Commented:
Thanks both, for the prompt responses.

I think I'm a bit stuck because of the switch; I dont think it supports the routing required. Replacing it with one that does is not an option at this point.

However, if I were to set all the machines I wanted on the scope with static IP addresses ( thru and the set DNS and gateway as appropriate, everything should still work as I want right? I just dont get the convenience of DHCP.

QlemoBatchelor and DeveloperCommented:
This question has been classified as abandoned and is being closed as part of the Cleanup Program. See my comment at the end of the question for more details.
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