alternate nameservers

I have a question for all you DNS gurus out there. I'd like to setup a domain so that it always goes to my main server unless that server is down, in which case it goes to my alternate server. Can I just set the site up as a virtual site on both servers and then set the nameservers on the domain like this:

NS1: ns1.mainserver.com
NS2: ns2.mainserver.com
NS3: ns1.alternateserver.com
NS4: ns2.alternateserver.com

Will this work the way I think it will? is there anything else that I'm not realizing that I should consider?

Thanks in advance for your help.

 

 

 

 

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