Good Morning,

I am a network administrator for a small charity-based organization in the states.  My predecessor -- (the individual who configured most of this environment) -- set up two primary DHCP servers -- one with a 192.168.2.xx scope, and one with a 192.168.3.xx scope.  What I intend to do is to consolidate these two scopes into a super-scope on our DC, then set up a split-scope on the alternate server.  What can I say?  I like things to be consolidated. 

Unfortunately, I'm running into a problem I haven't seen before, and am hoping to get some advise.

So here's what I did (In order) to transfer the 3.xx scope over to our DC.

1. On DC - Added new scope under our super-scope. Activated.

2. On 3.xx DHCP server - inactivated 3.xx scope.  (Being cautious, I inactivated the scope so that if everything didn't work I could easily switch it back on)

3. On a 3.xx PC - cmd prompt, ipconfig /release, net dhcp stop, net dhcp start, ipconfig/renew.  After about a minute or so it says the task couldn't be completed; event viewer gives me the following error: "Your computer was not assigned an address from the network (by the DHCP server) for the network card with network address (blah).  The following error occurred: 0x79.  Your computer will continue to try and obtain an address on its own from the network address (DHCP) server. 

There are no event logs on the DC under Server Roles > DHCP Server. 

As soon as this test failed a few times, I went ahead and re-activated the scope on our 3.xx DHCP server. 

Only a small percentage of our computers actually use the 3.xx subnet, my PC included.  The 3.xx subnet was created by my predecessor (on the different server) back when our organization was running out of ip addresses.  Either way, there's no critical need to export/import the DHCP database -- a "new" scope on our DC is just fine. 

Now I know this probably won't be resolved with just what I've given you, so if anybody needs more information, just let me know what you need and I'll pull it up. 

Best Regards,

Rob

Addendum: Another issue is that, even if the primary DHCP server didn't accept the new 3.xx subnet, I would think that it would issue my test computer a 2.xx ip address in its place (we have plenty available). 

• Edited by Coolhead2015 Tuesday, May 26, 2015 5:10 PM

Hi,

According to your description, my understanding is that DHCP enable client cant obtain IP lease with error 0x79 after scope 192.168.3.xx has been moved from DHCP server to DC.

I recommend you to reference the steps below:
1. New scope(instead of superscope) 192.168.3.xx on DC.
2. If client and DC are on different subnets, configure DHCP proxy on intermediate devices(such as router), or add Windows DHCP proxy on subnet, in order to transfer DHCP message.
3. Active 3.xx scope on DC, and in-active this cope on original DHCP server.
4. On DHCP client, use ipconfig /release and ipconfig /renew to force the client to obtain IP lease from DC.

If client can successfully obtain IP lease from DC, then new superscope(with 2.xx and 3.xx scopes included) on DC. remember to change the settings on intermediate devices(routers, relay angents). Link below described about Superscope configurations for multinets, just for your reference:
https://technet.microsoft.com/en-us/library/cc757614(v=ws.10).aspx

If client failed to obtain IP lease, on the client, try to ping IP address of DHCP server. confirm the network connectivity. 

Best Regards,
Eve Wang