It does not get overwhelmed, the xor space means as nodes vanish there is another right there. (poking finger in the sea again). So to overwhelm a node you need to be connected (unlikely) and if you are then you use all your bw to try and dos whilst another 31 nodes try to speak to you, if you get one off another takes its place and you need to speak to it. You are surrounded by a different (somewhat) bunch of nodes so then you are in trouble.
In terms of ddos then you need to ddos the entire network really and you are not connected to that so need to hop across nodes who will filter you etc.
This is all xor networking etc. like trying to bring down bittorrents DHT, but with an awful lot more security in mind and no nodes accepting connections from nodes not near it or who improve the routing table. If oyu check my blog I do try and expalin some of this. More to follow when I am finished with routing_v2 which will show people very clearly what can be done with a secured DTH and why even that is not enough, but eons better than what exists.