MAC Address Overlap

What this MAC address mapping interview question tests

This is an easy networking question that probes understanding of how IPv4 multicast addresses are translated to MAC addresses at the link layer. It rewards knowledge of the Address Resolution Protocol (ARP) and the inherent limitations of the mapping scheme, rather than complex calculation or code.

The question asks you to identify a fundamental constraint: the IPv4 multicast address space is larger than the portion of MAC address space reserved for multicast. This mismatch creates a practical problem that network engineers and protocol implementers must account for. Strong answers explain not just that a problem exists, but why it arises from the sizes of the two address families and what the consequences are.

• IPv4 multicast address structure and scope
• MAC address allocation and IEEE 802 standards
• Address space cardinality and collision handling
• Link-layer protocol limitations