Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) v1.2InfrastructureMedium
A network engineer is configuring a new Cisco router that will serve as the default gateway for a critical server farm. To ensure high availability, the engineer needs to implement a solution where two routers can act as a single virtual router, sharing a virtual IP address and MAC address. If the primary router fails, the secondary router should automatically take over the active role without any disruption to the servers. Which Layer 3 redundancy protocol should be configured?
- AVRF-Lite (Virtual Routing and Forwarding Lite)
- BHSRP (Hot Standby Router Protocol)
- CBGP (Border Gateway Protocol)
- DOSPF (Open Shortest Path First)
Show answer & explanationAnswer & explanation
Correct answer: B. HSRP (Hot Standby Router Protocol)
HSRP (Hot Standby Router Protocol) is a Cisco proprietary FHRP (First Hop Redundancy Protocol) that allows two or more routers to share a single virtual IP address and MAC address, providing transparent failover for end devices when the active router fails.
Why the other options are wrong
- A. VRF-Lite provides virtual routing instances within a single router, not first-hop redundancy between separate routers.
- C. BGP is an exterior gateway routing protocol used for routing between autonomous systems, not for local gateway redundancy.
- D. OSPF is an interior gateway routing protocol, not a first-hop redundancy protocol.
First Hop Redundancy Protocols (FHRP)
Protocols that provide redundant default gateway services for end devices on a LAN, ensuring continuous network access even if a gateway router fails.
- Includes HSRP, VRRP, GLBP.
- Uses a virtual IP and MAC address.
- Transparent failover for end hosts.
Memory trick: FHRP is like having two doormen, if one rests, the other steps right in.