Question : Using an additional domain controller when PDC crashes

My company's network is small and located in office space.  We have a two domain controllers one on SBS 2008 and one on Windows 2008 Server.  The SBS is the main machine has FSMO roles and the global catalog server.  

My question is, can someone tell me or direct me to an article that would tell us what to do if the SBS server went down?

Thanks

Answer : Using an additional domain controller when PDC crashes

Correct if you have DHCP on your SBS which you should. Go to Admin Tools then select DHCP find your scope options. Add secondary to the below scope option.

6 DNS servers Specifies a list of IP addresses for DNS name servers available to the client.
http://technet.microsoft.com/en-us/library/cc958929.aspx