What is the primary basis for EIGRP's metric calculations?

EIGRP (Enhanced Interior Gateway Routing Protocol) uses a composite metric to determine the best route to a destination, and the primary basis for its metric calculations consists of bandwidth and delay parameters. Bandwidth reflects the maximum throughput of the link, while delay is the time required for a packet to traverse the path. By incorporating these two factors, EIGRP can evaluate the efficiency of a route more accurately. This is crucial in hybrid routing protocols, where optimal path selection is based not just on speed but also on the quality of the link.

Load and stability metrics, though factors in network performance, are not primary components of the EIGRP metric calculation. Similarly, considering only the interface speed would overlook the importance of delay in determining the best route. Lastly, the size of the routing table does not play a role in metric calculations; it simply indicates how many routes are being managed by the router.

Thus, the most accurate choice is indeed based on bandwidth and delay parameters, as they are integral to how EIGRP assesses and chooses the optimal path for data packets.