Which statement about Class D addresses is true?

• A. They are used for multicast and have no valid host addresses
• B. They are used for private networks
• C. They are reserved for loopback testing
• D. They are the broadcast class

Answer: (A)

Class D addresses are used for multicast communication, not for identifying individual hosts. They fall in the range 224.0.0.0 to 239.255.255.255, and traffic sent to a Class D address is delivered to all hosts that have joined that multicast group. Because the purpose is group delivery rather than one-to-one addressing, there isn’t a valid host portion for a Class D address.

That’s why the statement about being used for multicast and having no valid host addresses is the correct one. Private networks are defined in RFC 1918 and use specific non-Class D ranges (like 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16). Loopback uses the 127.0.0.0/8 range, not Class D. And “broadcast class” isn’t a real IPv4 class designation—broadcast is a separate concept related to delivering to all hosts on a network (like 255.255.255.255), not a Class D characteristic.