Network architecture and related methods for maintaining traffic flow between clients and an end-server during a Denial of Service (DoS) attack are described herein. The network architecture includes a set of overlay nodes coupled between clients and a server. Each overlay node is able to rank and probe other nodes for purposes of selecting a best path for routing traffic to the end-server to resist a denial of service of attack. Probing is performed to detect overlay nodes having better performance based on one or more performance metrics (i.e., load, jitter, latency, loss rate). For instance, in one implementation probing detects lightly loaded overlay paths for purposes of routing traffic to the end-server, so as to maintain connectivity between the end-server and clients even under DoS attacks.