Which information is used to install the best route to a destination in IP routing table?

A tunnel ID identifies a specific tunnel interface but is not a general criterion for determining the best route among different destination networks in the IP routing table.

Routers employ the longest prefix match rule to select the best route when multiple paths to a destination exist with the same administrative distance and metric. A longer prefix length indicates a more specific route, which is preferred for traffic forwarding.

The interface number specifies the outbound interface for a route but is not a criterion used to compare and select the best route to a destination from multiple available options.

An autonomous system (AS) is an administrative domain in routing, primarily relevant in BGP. While BGP uses AS paths, the AS itself is not the general information used to install the best route in the IP routing table across all routing scenarios; prefix length is more fundamental.