Which statement correctly describes how IPv6 multicast addressing works when packets are sent to a multicast address?

Introduction / Context:
IPv6 relies heavily on multicast instead of broadcast for efficiently delivering packets to multiple receivers. Understanding how multicast addressing behaves is important for grasping how protocols such as Neighbor Discovery, routing protocols, and service discovery operate in an IPv6 network.

Given Data / Assumptions:

• An IPv6 multicast address can represent a group of interfaces.
• Any interface that wants to receive packets for that group must join the multicast group.
• Routers forward multicast packets according to group membership rather than flooding them everywhere by default.
• The question asks which description of multicast behavior is correct.

Concept / Approach:
Multicast communication is known as one-to-many or many-to-many. When a packet is sent to a multicast address, it is delivered to all interfaces that are members of the associated multicast group. These interfaces may exist on the same link or across multiple links, depending on routing and group membership. This is very different from unicast, which targets a single interface, and from broadcast, which targets all interfaces on a segment whether they asked to receive the traffic or not.

Step-by-Step Solution:
1. Recall that multicast addresses identify a group of interested receivers rather than a single device.2. When a sender transmits a packet to a multicast group address, all interfaces that joined the group are supposed to receive the packet.3. This behavior is described as one-to-many because one sender can efficiently reach many receivers.4. Examine the answer choices to find the statement that matches this behavior.5. Option B states that packets are delivered to all interfaces identified with the address and refers to one-to-many communication, which aligns with how multicast operates.

Verification / Alternative check:
In practice, when you configure an application or protocol to join an IPv6 multicast group, packet captures will show that it receives packets sent to that group address. Multiple hosts on the same subnet can join the same group and all receive the same multicast transmission. Multicast routing protocols extend this concept across multiple networks.

Why Other Options Are Wrong:
Option A describes unicast, not multicast, because it states that packets are delivered to a single interface. Option C is effectively describing anycast, where one of several possible receivers gets the packet, often the nearest one, not multicast. Option D incorrectly claims that multicast addresses are only for nonrouting purposes and focuses on address overlap, which is not the core property being tested here.

Common Pitfalls:
Learners sometimes confuse multicast with broadcast or anycast. Broadcast sends to everyone on a local segment, while multicast sends only to interested group members. Anycast sends to exactly one member of a group of potential receivers. Keeping these three modes distinct is crucial for understanding modern IP networking, especially in IPv6 where multicast replaces many traditional uses of broadcast.

Final Answer:
Packets addressed to a multicast address are delivered to all interfaces that have joined that multicast group, which is called one-to-many communication.