Which MAC address represents an IP multicast address?

Which MAC address represents an IP multicast address?

• A. CF-00-00-00-00-00
• B. 01-00-5E-0F-0F-0F
• C. FF-FF-FF-FF-FF-FF
• D. 00-00-0C-F0-F0-F0

Answer: (B)

IPv4 multicast at the Ethernet layer uses a specific MAC address prefix to indicate a group delivery. The first three octets must be 01-00-5E, signaling that this is a multicast MAC. The remaining 23 bits carry the lower part of the IP multicast group address, but the key identifying feature is that 01-00-5E prefix. Among the options, the one that begins with 01-00-5E is the multicast MAC. The other addresses do not use this multicast prefix (one is a broadcast address, one is a unicast-like address, and the last is not in the multicast range), so they do not represent an IP multicast MAC.

IPv4 multicast at the Ethernet layer uses a specific MAC address prefix to indicate a group delivery. The first three octets must be 01-00-5E, signaling that this is a multicast MAC. The remaining 23 bits carry the lower part of the IP multicast group address, but the key identifying feature is that 01-00-5E prefix.

Among the options, the one that begins with 01-00-5E is the multicast MAC. The other addresses do not use this multicast prefix (one is a broadcast address, one is a unicast-like address, and the last is not in the multicast range), so they do not represent an IP multicast MAC.