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Two routers, R1 (192.168.1.2) and R2 (192.168.1.3), are configured with VRRP using the virtual IP address 192.168.1.254. Normally R1 forwards traffic as the master. Which address should be set as the default gateway on the LAN hosts?

  1. A192.168.1.2 (R1's address)
  2. B192.168.1.3 (R2's address)
  3. C192.168.1.254 (the virtual IP address)
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Answer: C. 192.168.1.254 (the virtual IP address)

VRRP lets several routers form one virtual router that shares a virtual IP address and a virtual MAC address. Normally the master router forwards packets sent to the virtual address, and if the master fails, a backup router becomes the master and takes over forwarding. If hosts use the virtual IP address as their default gateway, they need no change whichever router is running. Mechanisms like this that make the default gateway redundant are collectively called FHRPs, and besides VRRP they include HSRP and others.

  • A. If R1 fails, hosts configured with this address can no longer communicate outside the LAN.
  • B. If R2 fails, hosts lose connectivity, so there is no benefit from redundancy.
  • C. Correct. The virtual IP address works whichever router is forwarding.
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