N10-009 Question 91
Single answerTraffic types: Unicast, Multicast, Anycast, BroadcastA company is deploying a live training platform to 300 employees on the same campus network. During testing, the video server sends a separate stream to each user, and the uplink to the server becomes saturated. The network administrator wants a traffic-delivery method that allows the server to send one stream that is replicated only for hosts that joined the session, while avoiding delivery to devices that did not request the training. Which traffic type best meets this requirement?
- A
Unicast
- B
Multicast
- C
Broadcast
- D
Anycast
Show answer and explanation
Correct answer: B
Explanation
The correct answer is Multicast. In a real-world enterprise video or training deployment, multicast allows a source to send one stream to a multicast group, and the network forwards it only to segments with interested receivers. This is more efficient than unicast for large audiences because the source does not have to generate hundreds of duplicate streams. It is also more selective than broadcast because non-participating hosts do not receive the traffic. By contrast, unicast is one-to-one, broadcast is one-to-all within a broadcast domain, and anycast is one-to-nearest-one among multiple equivalent destinations. This aligns with standard networking behavior described in common vendor documentation and certification objectives, including the use of multicast group membership mechanisms such as IGMP in IPv4 environments.
- A. Incorrect.
Unicast is one-to-one communication. In this scenario, sending a separate unicast stream to each of 300 employees is exactly what caused the server uplink to become saturated. While unicast is common for many applications, it does not efficiently solve one-to-many content delivery on the same network when many users need the same stream.
- B. Correct.
Multicast is correct because it is designed for one-to-many delivery where only interested receivers join the group. The sender transmits a single stream to a multicast group address, and network devices replicate traffic only where needed for subscribed hosts. This reduces bandwidth consumption compared with separate unicast streams and avoids sending the traffic to endpoints that did not join the session.
- C. Incorrect.
Broadcast is incorrect because broadcast traffic is sent to all devices within the broadcast domain, whether they requested the traffic or not. That behavior would waste bandwidth and processing on hosts that are not participating in the training session. Broadcast is appropriate for limited purposes such as ARP in IPv4, not for efficient delivery of streaming media to selected users.
- D. Incorrect.
Anycast is incorrect because anycast is used to direct a client to the nearest or best one of multiple possible receivers sharing the same address, commonly for services such as DNS or content delivery. It is not used to distribute a single stream simultaneously to many subscribed endpoints. A common misconception is to confuse anycast with one-to-many delivery, but anycast is effectively one-to-nearest-one.