OK - I went ahead and set up the other 3 DNS sites as secondary servers. I had a bit of trouble with vcsweb, (strav.com, strav.net, and egiveit.com showed errors, but zilliox.us didn't even though they were all set up the same). I sent an e-mail to support at vcsweb and they responded quickly that they were confused as well and that zilliox.us should be displaying the same errors. These errors should disappear once the delegation (registration of name servers at the registrar level - Dotster in my case) is complete. So, within 72 hours, I should have 8 nameservers from 5 different companies for each of the sites. That should pretty much eliminate outages from DNS attacks. :)