What happens to the drk network when some masternode servers get hacked? If anyone can run them, do we all just trust that the individual's pc's have adequate protection??
I think DDOS attacks on the masternodes will be a big issue.
Absolutely! The network relies on masternodes being safe, secure, and online. When these get hacked the dark network could be in lots of trouble

The implementation is fault resistant. If one goes down, it will be quickly discovered and removed from the list and the rest will remain active.
I know there is supposed to be built in DDOS protection in the master nodes, but with my experience in IT i know nothing is fullproof, even with linux, you can still be prone to DDOs attacks, and look at all the mining pools ive been mining on, most of them run on linux, and supposed to have DDOS protection, yet many pools have been affected.
Its very likely this could happen to master nodes, and if there is a big enough attack from a botnet for instance, whats there to stop it from shutting down each masternode one by one?
Even if a few nodes got attacked it could cause havoc.
Masternode is on top of Darkcoin p2p network.