Cisco Certified Network Associate (CCNA) Practice Exam

Which multicast address does the VRRP virtual router master use for sending advertisements?

1. 224.0.0.9

2. 224.0.0.18

3. 239.255.255.255

4. 224.0.0.20

The correct answer is: 224.0.0.18

The Virtual Router Redundancy Protocol (VRRP) utilizes a specific multicast address to facilitate communication between the master and backup routers within a VRRP group. The correct multicast address used by the VRRP virtual router master for sending advertisements is 224.0.0.18. This address is designated for use by VRRP and allows the routers in the group to efficiently send advertisement messages to all members of the group without requiring each router to be configured with a unique destination address. By using the multicast address, VRRP ensures that advertisements are received by all routers that need to recognize and respond to the master router's messages. In contrast, other addresses listed are designated for different purposes or protocols. For example, 224.0.0.9 is used by the Routing Information Protocol (RIP), while 239.255.255.255 is a local multicast address. Similarly, 224.0.0.20 is assigned for other multicast applications. Understanding the specific usage of multicast addresses is key in network protocols, as they help optimize communication and resource utilization in a network environment.