How does a GLBP cluster respond to a host ARP request for the virtual IP address?

The AVG is the sole router responsible for answering ARP requests for the shared virtual IP address. It responds with one of the configured virtual MAC addresses (format 0007.b400.xxyy), assigning different virtual MACs to different requesting hosts to achieve load balancing across multiple AVFs. This mechanism is what distinguishes GLBP from HSRP and VRRP, which do not provide per-host load balancing.

AVFs forward traffic using their assigned virtual MAC addresses, not their own hardware MACs, and they do not respond to ARP requests - only the AVG handles ARP for the virtual IP.

GLBP load balancing is controlled by the AVG assigning virtual MACs in a round-robin or weighted manner; individual routers do not independently respond to ARP based on their utilization.

The AVG responds with a virtual MAC address, not its own hardware MAC address - using its hardware MAC would prevent load balancing because all hosts would send traffic to only one physical router.