[ropiku]

It's not that hard but DynDNS can offer a much higher performance, reliable and advanced service. They use anycast with a lot more servers than it's practical for each company to manage. They also offer advanced georouting, failover, etc.

In the face of a DDoS I'm not sure a custom nameserver network would do much better than a company who does that for a living. The only advantage is that attacks would have to target individual services (which did happen other times).