I have a ded. server and also and account as a reseller in another server Since I'm newbie in server management I want to have my ded server as the backup in case that my provider is down. Most of my domains are in godaddy. If I put the 3rd and 4th choice on the DNS for the ded. server and for some reason my reseller acccount goes down...will the ded. server be able to show the pages? or should I put my ded. server as the second dns choice? will this work at all? if not how?
No, this will not work, since your domain will be most likely pointing to ns1.yourdomain.com and ns2.yourdomain.com. If the server that has the IPs for those nameservers goes down, so will your domain.
If you add ns3.yourdomain.com and ns4.yourdomain.com to the nameservers for yourdomain.com, you will create a round-robin situation, where sometimes people will get the pages on your reseller account, and sometimes they will get the pages on your dedicated server.