正解:B
The active next hop IP address for the subnet 192.168.102.0/24 when the primary IP address 192.168.101.2 fails would be 192.168.101.6. This is based on the IP routing protocols and redundancy mechanisms such as HSRP, VRRP, or GLBP, which are designed to provide high availability by allowing multiple routers to work together to present the appearance of a single virtual router to the hosts on the LAN. The specific active next hop would depend on the priority and tracking configuration of these protocols on the routers in question.
References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) training material provides a comprehensive guide on configuring, verifying, troubleshooting, and optimizing next-generation, Service Provider IP network infrastructures, including details on high-availability mechanisms and IP routing protocols1