Which class is associated with multicast use in IPv4 classful addressing?

• A. Class D
• B. Class A
• C. Class B
• D. Class C

Answer: (A)

In IPv4 classful addressing, multicast uses a dedicated address class. This space is Class D, spanning 224.0.0.0 to 239.255.255.255. Unlike the unicast classes (A, B, and C), which assign addresses to individual hosts with default masks of /8, /16, and /24, Class D identifies a multicast group rather than a single endpoint. A packet sent to a Class D address is intended to be delivered to all members of the multicast group that have joined that group, enabling one-to-many delivery.