Two SBS on same LAN

cjohnson300
cjohnson300 used Ask the Experts™
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I have inherited a network from a company acquisition that has two Small Business Servers (2003 and 2008) on the same LAN.  

They are aware of the problems and reasons why this is not a good idea, so I dont want to go into that too much, but does anyone know if the two of them will constantly chatter to each other about who is in charge, generating a high amount of unrequired network traffic across the LAN?

All comments on network related problems due to the two SBS are greatly appreciated

Many thanks
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There are two reasons why it's not a good idea to have 2 SBS servers on the same LAN:
1. It's a violation of Microsoft's licensing agreement. They only allow one small business server per network.
2. If the two SBS servers find out about one another, they will start to reboot on a regular basis and log events concerning having other SBS servers. I was unfortunate enough to be in the situation once with a consulting client of mine. He had accidentally restored a backup of an SBS server and it was on the same domain as the live one and they started rebooting regularly. To be clear, though, these two servers were both on the same network and part of the same active directory domain. If yours are not part of the same domain (or have somehow been hacked so they can have two on the same domain), you may not be experiencing the reboot issue. You would still be in violation of #1, though.

Other than that, though if you're not experiencing any direct reboot issues that's the only technical consequence that will result.
David AtkinTechnical Director
Top Expert 2015
Commented:
DHCP and DNS will be your biggest issue here.  If you have both servers providing the DHCP service then it will cause an issue.

DHCP will need disabling on one of the servers.  If SBS detects another DHCP server on the network then it will shutdown its DHCP service.

DNS will be an issue if they are looking at the wrong servers for lookups.

I would advise moving away from this configuration.  I would look at decommisioning the SBS 2003 and moving everything to the SBS 2008 if possible.  You would have to do this manually now as the SBS 2008 is already in a working environment.

Julian123's comments are valid with regards to the licencing etc.
Alan HardistyCo-Owner
Top Expert 2011
Commented:
You can have two SBS servers on the same LAN as long as the domain names are different.  If they are both on the same domain name, then one will shut down hourly as you will be breaching the license agreement.
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And, note that if the users connect to both SBS for any reason... file shares, LOB apps, RWW, they will need CALs for both.

But the advice above is (mostly) correct.  Different domains, turn off DHCP on one, static IP for the stations that are joined to that one.

Author

Commented:
Many thanks to all you responded
Lee W, MVPTechnology and Business Process Advisor
Most Valuable Expert 2013

Commented:
I want to clarify and correct:

It is NOT a licensing violation to have two SBS servers on the same LAN.  It is a license violation to hack one of them to allow them to be in the same DOMAIN for any significant length of time (Migrations PERMIT two on the same domain for up to 3 weeks).  The only significant issue with having two on the same LAN is DHCP - which has been correctly addressed above (one or both domains would use static addressing).  And you also would want to keep all names unique - don't call set both servers names the same like "SBSSERVER" and don't setup clients so they have the same names either (though that's just to prevent oddities that might occur from time to time).

And just to be clear, the LAN is the physical network - the DOMAIN is the logical grouping of computers - regardless of physical network.

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