Final answer:
Employing a CDN is the best technique to protect an application server against resource exhaustion attacks in a large-scale DDoS attack.
Step-by-step explanation:
The best technique to survive a large-scale DDoS attack and protect an application server against resource exhaustion attacks is to employ a Content Delivery Network (CDN).
A CDN is a network of servers distributed geographically, which helps to distribute the incoming traffic and serves the content to users from the closest server. This reduces the load on a single server and helps in mitigating DDoS attacks.
By spreading the traffic load across multiple servers, a CDN can absorb and handle the excessive traffic, providing a higher level of availability and scalability to the application server.