Which load balancing method uses the client’s IP address to select the backend server, helping maintain session affinity?

• A. Round Robin
• B. Least Connections
• C. IP Hash
• D. Weighted Round Robin

Answer: (C)

Session affinity is achieved when a load balancer routes requests from the same client to the same backend server. Using the client’s IP address to pick a backend accomplishes this by applying a hash to the IP and mapping that result to a specific server. Because the IP is deterministic, the same client IP will consistently land on the same server as long as the server pool and mapping stay the same, preserving the session state on that server.

This approach is different from round robin, which distributes requests without regard to who is making them; least connections, which aims for the fewest active connections on the chosen server; and weighted round robin, which distributes based on configured weights but doesn’t tie a particular client to a single server. The trade-off is that changes in the server pool or a client changing IPs (such as moving between networks) can disrupt the mapping and affect the session.