using multiple name servers to point at two web servers

I have a dedicated server and a reseller account on a hosting provider and I want to have the dns setup to point to the reseller server if the dedicated server goes down.

So I mirrored the domains on the dedicated server with the reseller server and added these name servers for all my domains…

So will this work or not if my dedicated server crashes?

ns1.dedicated_server.com
ns2.dedicated_server.com
ns1.reseller_server.com
ns2.reseller_server.com

thanks,
Bob