Understand a default gateway.
Default gateway failure and failover
A PC normally uses one configured default gateway. Even if another router is nearby, the PC does not automatically know that it should change gateways when the first router fails. A first-hop redundancy protocol can present a shared virtual gateway address.
HSRP is a Cisco first-hop redundancy protocol. In a simple group, one router is active and another is standby. Hosts use the virtual IP address as their gateway, while the routers still have their own interface addresses. VRRP is another redundancy protocol. Their terminology and configuration details differ.
Dependencies affecting network availability
A working virtual gateway does not guarantee that the router has a working upstream path. Tracking can influence router priority based on a watched condition. Preemption controls whether an eligible higher-priority router can take over; behaviour depends on the protocol and configuration.
For CCNA, focus on the purpose and forwarding idea. For a lab, draw two gateways on the same LAN, a shared virtual address and independent paths beyond them. Plan return routes too. If both gateways depend on one failed switch or power source, they share a failure point.
Practical exercise
PCs use virtual gateway 192.168.10.1. R1 has .2 and R2 has .3. When R1 fails, should every PC have its gateway changed to .3?
Show the answer and explanation
No. With functioning first-hop redundancy, the virtual gateway remains .1 and the eligible backup takes over its role. End-to-end connectivity still depends on the remaining path.
QUICK KNOWLEDGE CHECK
Check your understanding
Related labs and exercises
Sources & content checks
Technical references checked on 25 October 2026. These are original teaching explanations, not official Cisco course material. See how content and lab validation are described.
Your progress
Mark this complete when you can explain the example and do the exercise.