Which of the following devices would be MOST useful to ensure availability when there are a large number of requests to a certain website?

A protocol analyzer (packet sniffer) captures and inspects network traffic for troubleshooting or analysis but does not distribute requests or improve server availability.

A load balancer sits in front of a pool of servers and distributes client requests using algorithms such as round-robin or least-connections, preventing any single server from becoming a bottleneck. This directly improves availability and fault tolerance for high-traffic websites by spreading the load and allowing failed servers to be bypassed automatically.

A VPN concentrator manages and aggregates VPN tunnels for remote access, not for distributing web traffic across servers.

A web security gateway filters web content for threats such as malware and inappropriate sites but does not balance or distribute traffic to improve availability.