[retronick]

Really, the best thing you can do is make certain you're with a good, stable, Anycast provider. Preferably one that's been beefing up their network. I've been using DNS Made Easy for a few months now for the ability to have vanity name servers and have noticed a significant boost in speed since. I also started using their failover service to help avoid going down since they included 3 records with my membership anyway :P. They're also crazy cheap for the features I'm been getting: http://www.dnsmadeeasy.com/enterprisedns/pricing.html

As for why Namecheap got hit, who knows. Could be a malicious attack on a site using the service, could be a prank. Maybe just for lolz. There's any number of reasons. Unless they release that info, I don't think you'll find a clear answer any time soon :-/.