I have been reading many posts on serverfault as well as on other sites regarding all these.
What I understand is, Multiple A records(round-robin dns) can be used for both :
Load sharing (round-robin, but NOT load-balancing). Many people say that “Load Balancing” but I think there will be no load-balancing because “Balance” means (literally) “compare two(or more) and adjust” (and that is what Real s/w or h/w Load balancers do) but Browsers never do this, instead they randomly select an IP and connect to it. It doesn't have any knowledge about the current load of that server (probably, the IP it picked had the highest load!).
Automatic failover (latest browsers only). Yes, I think DNS can be used as a simple failover system (at least in 2012, I dont know when it actually "came in effect"). please refer to : http://webmasters.stackexchange.com/questions/10927/using-multiple-a-records-for-my-domain-do-web-browsers-ever-try-more-than-one and Browser-based DNS failover using multiple A records and http://www.nber.org/sys-admin/dns-failover.html
I would like to make sure my assumptions/findings are right. So let me know please.....