IP addressing fundamentals: which statement correctly describes a multicast address in IP networking?
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APackets addressed to a unicast address are delivered to a single interface.
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BPackets are delivered to all interfaces identified by the address. This is also called a one-to-many address.
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CIdentifies multiple interfaces and is only delivered to one address. This address can also be called one-to-one-of-many.
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DThese addresses are meant for nonrouting purposes, but they are almost globally unique so it is unlikely they will have an address overlap.
Answer
Correct Answer: Packets are delivered to all interfaces identified by the address. This is also called a one-to-many address.
Explanation
Introduction / Context:In Internet Protocol (both IPv4 and IPv6), addresses can represent different delivery semantics. Understanding the distinction between unicast, multicast, anycast, and special-purpose addresses is essential for routing, switching, and application design (for example, streaming or conferencing).
Given Data / Assumptions:
- The question asks specifically about multicast addressing.
- We compare multicast behavior with unicast and other types described in the options.
- No numeric calculation is required; this is a conceptual classification question.
Concept / Approach:Unicast delivers one-to-one, multicast delivers one-to-many, anycast delivers one-to-one-of-many (nearest instance), and broadcast (IPv4 only) delivers one-to-all within a broadcast domain. Multicast uses group addresses joined by receivers; senders transmit once and the network replicates as needed.
Step-by-Step Solution:
Identify what multicast means: delivery to a set of interested receivers that have joined a group.Map this to option language: “delivered to all interfaces identified by the address” and “one-to-many.”Exclude unicast (single interface) and anycast (one-to-one-of-many).Confirm that the remaining descriptions do not match multicast semantics.Verification / Alternative check:Recall IPv4 Class D range (224.0.0.0 to 239.255.255.255) or IPv6 multicast prefix ff00::/8, both defined for one-to-many delivery where receivers explicitly join groups.
Why Other Options Are Wrong:
- A: Describes unicast (one-to-one), not multicast.
- C: Describes anycast; traffic goes to one (typically nearest) member of a set, not all.
- D: Sounds like unique local or special addresses; not a multicast definition.
Common Pitfalls:Confusing anycast with multicast and assuming multicast means broadcast. In multicast, only joined receivers get the traffic; it is not flooded everywhere.
Final Answer:Packets are delivered to all interfaces identified by the address. This is also called a one-to-many address.