Cisco Certified Network Associate (CCNA) Practice Exam

Which multicast address is used by HSRP for hello messages?

1. 224.0.0.104

2. 224.0.0.102

3. 239.255.255.250

4. 192.168.1.1

The correct answer is: 224.0.0.102

The multicast address used by HSRP (Hot Standby Router Protocol) for hello messages is 224.0.0.102. This address specifically corresponds to the HSRP protocol and is utilized by HSRP routers to send and receive hello messages, enabling them to determine the status of other routers in the group. When a router sends HSRP hello messages, it targets this multicast address, allowing all routers in the same HSRP group to listen for these messages and subsequently learn which router is currently in the Active role and which one is in the Standby role. The other multicast addresses provided do not serve this function in the context of HSRP. For instance, 224.0.0.104 is used by the PIM (Protocol Independent Multicast) protocol, while 239.255.255.250 is utilized for the SSDP (Simple Service Discovery Protocol). Lastly, the address 192.168.1.1 is a private IPv4 address generally used for local network devices and is not a multicast address at all. Therefore, recognizing 224.0.0.102, as designated for HSRP, is crucial for understanding how this protocol facilitates router redundancy through its hello messages.