Five Azure VMs (Windows Server 2016) are web servers behind load balancer LB1. Ensure visitors are always served by the same backend server for each request. What setting should you change?

To ensure visitors are always served by the same backend server (session stickiness), you need to configure session persistence on the load balancer. Setting session persistence to "Client IP and protocol" (also known as Source IP affinity) directs subsequent requests from the same client IP address to the same backend instance. Using UDP as the protocol is incorrect because web traffic typically uses TCP, and changing the protocol doesn't address session persistence. Setting session persistence to "None" would distribute each request to any available backend instance, breaking session stickiness. Disabling Floating IP (Direct Server Return) is a setting related to how the load balancer handles response traffic, not session persistence.