Cisco CCNA (200-301)IP ConnectivityHard
A network segment has two routers, R1 and R2, configured for HSRP. R1 has a priority of 150, and R2 has a priority of 100. Both are configured with `standby 1 ip 192.168.1.254`. The `standby 1 preempt` command is configured on R1, but NOT on R2. If R1 fails and then recovers, what will be the state of R1 and R2?
- ABoth R1 and R2 become Active.
- BBoth R1 and R2 become Standby.
- CR1 becomes Standby, R2 remains Active.
- DR1 becomes Active, R2 becomes Standby.
Show answer & explanationAnswer & explanation
Correct answer: D. R1 becomes Active, R2 becomes Standby.
HSRP preemption allows a router with a higher priority to take over the Active role if it comes online or recovers. Since R1 has a higher priority (150) and preemption is enabled on R1, when R1 recovers, it will preempt R2 and become the Active router. R2 will then transition to the Standby state.
Why the other options are wrong
- A. Only one router can be Active at a time in a stable HSRP group.
- B. This is incorrect; one router must be Active to provide gateway services.
- C. This would happen if preemption was NOT enabled on R1, or if R2 had a higher priority.
HSRP Preemption
HSRP preemption allows a router with a higher configured priority to assume the Active role immediately if it comes online or recovers, even if another router is currently Active.
- Enabled with the `standby [group] preempt` command.
- Ensures the preferred (higher priority) router is always Active.
- Without preemption, the first router to become Active stays Active until it fails.
- Can lead to flapping if not carefully managed (e.g., with interface tracking).
Memory trick: Preempt is the king's right, to take the throne with all its might.