Your company has implemented HSRP for IPv6, and clients use a virtual default gateway. However, when the active router fails, hosts cannot reach external networks.
Correct Answer: A
Detailed Explanation: In an IPv6 network using HSRPv6 (Hot Standby Router Protocol for IPv6), clients rely on a virtual default gateway to communicate outside their local subnet. However, IPv6 hosts do not use ARP like IPv4; instead, they rely on Router Advertisements (RAs) from routers to learn their default gateway. Why Ensuring IPv6 RAs Are Enabled is Critical? HSRPv6 provides a virtual IP address, but hosts still need a method to learn about it. Unlike IPv4, where hosts configure a static default gateway, IPv6 typically uses Stateless Address Autoconfiguration (SLAAC) or DHCPv6. If the active router in HSRPv6 fails, the standby router becomes active, but it may not send RAs unless explicitly configured. The command to enable IPv6 RAs on the interface is: interface GigabitEthernet0/0 ipv6 nd ra enable Why Other Options Are Incorrect? B (Incorrect): HSRPv6 does not require static routes on end hosts. The issue is more likely with Router Advertisements. C (Incorrect): Priority affects which router is active, but it does not explain why failover is not working. D (Incorrect): VRRP is a different redundancy protocol. It does not impact HSRPv6.
This CCNA practice question helps students prepare for Cisco networking certification exams by testing knowledge of network fundamentals, routing, switching, and network security concepts.