Backup DHCP Servers - 1 Failed, other running.

Hey All,

I have 1 server running SBS 2003 and another running 2008.

I had only 1 DHCP server running on 2003 and none on 2008.  I wanted a backup DHCP server.  So, as I was taught I setup a backup DHCP server by virtually splitting up the scope and setting reservations for each side.

It seemed to be working but within a few days SERVER1 (SBS) will not start the DHCP Server service and gives me an error message "The DHCP Server service on Local computer started and then stopped. Some services top automatically if they have no work to do, for example, the Performance Logs and Alerts service."

Any help or advice?


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Rob WilliamsCommented:
SBS has a built-in "feature" that will shut down it's own DHCP server/service if it sees another DHCP server on the same network segment. You cannot have 2 DHCP servers in an SBS domain.
Try to disable DHCP rogue detection by creating the following registry entry.

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Servic es\Dhcpserver\Parameters

On the Edit menu, click New->DWORD Value, and then add the following registry value:

Value name: DisableRogueDetection
Data type: REG_DWORD
Radix: Binary
Value data: (Hexadecimal) 1, which will be saved as 0x00000001

Restart the server.

That will disable SBS checking for another DHCP server. Then you can go ahead and split the subnet between two servers. This approach is a little risky, though. I'm not sure how it will influence the DNS and Active Directory on your SBS network.

Some considerations available here:
ArdentJWAuthor Commented:
Well I do not want to put my network at risk.  But I thought it wise to split the scope amongst 2 DHCP servers using 80/20 or 50/50.  That isnt a bad idea right?  Its just an SBS problem I take it?

Why would rogue detection be an issue?  Both DHCP servers were setup by administrators and authorized to be used in AD.  They should play nice! lol
- James
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The CompTIA Cloud+ Basic training course will teach you about cloud concepts and models, data storage, networking, and network infrastructure.

It's hard to give suggestions not knowing the situation in-depth. But you seem like the person who can make decisions responsibly enough.

So if you see no problem with your setup, go ahead and do it! You're the boss! :)
ArdentJWAuthor Commented:
I solved the problem, though not ideally, by setting SERVER2 (2008) dhcp server service to disabled THEN starting Automatic DHCP server service on SBS.  Then setting SERVER2 to Manual.

If my primary DHCP server goes down, SBS, then I can always go in and manually start the service for DHCP network service.

- James

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Rob WilliamsCommented:
Curious as to why you are deleting the question.
As mentioned SBS MUST be the DHCP server and no other present. SBS is not Server 2003, and does have several limitations, most of which are related to the fact that it is not an enterprise solution, but rather for small businesses of less than 75 users.
You really do not have a fault tolerant network with having a second one which you can manually enable. You could just as easily enable on a router if that were the issue. Also the odds of the SBS DHCP service failing and not being able to restart it manually is less than 1/1000.

If you do want to have an alternate DHCP service (with manual start), make sure you add all the SBS DHCP scope options. It adds more scope options than are used in most situations. In addition if you use other than the SBS DHCP service you may find features such as the SBS integrated VPN will not work.

I guess my main point is that the reason your back up DHCP service failed is due to the fact that it is not supported by SBS. Therefore I do not see deleting the question as the correct reason/solution was given.
Rob WilliamsCommented:
Thanks ArdentJW.
Cheers !
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