Cisco CCNA (200-301)IP ConnectivityEasy
A small office has two routers acting as redundant default gateways for the LAN using a First Hop Redundancy Protocol. What is the primary purpose of this configuration?
- ATo provide a virtual IP and MAC address so hosts have continuous default gateway service if one router fails
- BTo load-balance DNS queries between the two routers
- CTo allow both routers to share the same physical interface
- DTo synchronize the routing tables of both routers using OSPF
Show answer & explanationAnswer & explanation
Correct answer: A. To provide a virtual IP and MAC address so hosts have continuous default gateway service if one router fails
First Hop Redundancy Protocols (HSRP, VRRP, GLBP) present a shared virtual IP/MAC address to hosts so that if the active/primary router fails, a standby router transparently takes over as the default gateway.
Why the other options are wrong
- B. FHRPs are not related to DNS load balancing.
- C. Routers each keep their own physical interfaces; they do not share one physical interface.
- D. FHRP is unrelated to routing table synchronization protocols like OSPF.
First Hop Redundancy Protocol (FHRP)
A protocol that provides transparent failover of the default gateway using a shared virtual IP and MAC address.
- Examples: HSRP (Cisco), VRRP (standard), GLBP (Cisco, load balancing)
- Hosts are configured with the virtual IP as their gateway
- Active router forwards traffic; standby takes over on failure
Memory trick: One virtual door, two guards ready to swap in.