Sahil

well no there isnt any other way....other than moving to a different host (mostly a paid one)... because no else provides free hosting as good as Heliohost..

No backup dns servers wont hold the web site alive. they would just hold ur DNS records until they expire (i think so).... because the website requires a web server for loading..

i dont think u can setup secondary dns from cpanel... anyways,why do u want to setup secondary dns ??