alt Hacker NewsNot that I disagree with the fact that these risks exist, but how is that different than running any other service for a mission critical platform?
The main thing I can think of is DNS amplification attacks, but that's more your DNS server being used as part of a DDoS attack rather than being targeted for one. Also (afaik) resolvers are more common targets for DNS amplification than authoritative.
Large scale dns vendors have a multi million dollars worth of network layer traffic filtering equipment pipelined in front of their DNS servers (or in house solutions such as Google).