It takes a lot of energy to keep information correctly updated while it is being changed. Anyone who has been Hostmaster for even a moderately sized ISP knows there is an amazing number of ways for people to err. And it's important to realize that one can't assume that IP addresses that are numerically contiguous represent hosts that are topologically close on the network. However, the addresses are in fact routed to very diverse locations on Genuity's network. These servers are also geographically diverse.
Software is a bitch.
But the notion behind diversity isn't that diversity is error-free, it is that the error, whatever it is, is unlikely to strike more than one hardware platform or more than one OS or more than one application at a time. So here you are. Try using UltraDNS on half your DNS servers and BIND on the other half. And don't be like Microsoft. The incident happened on Sunday morning, and utility company officials hoped that customers would have power again late Monday evening.