We consider the problem of designing scalable and robust information systems based on multiple servers that can survive even massive denial-of-service (DoS) attacks. More precisely, we are focusing on designing a scalable distributed hash table (DHT) that is robust against so-called past insider attacks. In a past insider attack, an adversary knows everything about the system up to some time point t0 not known to the system. After t0, the adversary can attack the system with a massive DoS attack in which it can block a constant fraction of the servers of its choice. Yet, the system should be able to survive such an attack in a sense that for any set of lookup requests, one per non-blocked (i.e., non-DoS attacked) server, every lookup request to a data item that was last updated after t0 can be served by the system, and processing all the requests just needs polylogarithmic time and work at every server. We show that such a system can be designed.