N10-009 Question 90
Single answerTraffic types: Unicast, Multicast, Anycast, BroadcastA company is deploying a live video stream from a training server to 120 employees on the same campus network. During testing, the network team notices the server is sending 120 separate streams, causing high bandwidth usage on the access and distribution links. The team wants the server to send one stream that can be delivered efficiently only to employees who joined the training session, without sending the traffic to every host on the subnet. Which traffic type should the team implement?
- A
Unicast
- B
Broadcast
- C
Multicast
- D
Anycast
Show answer and explanation
Correct answer: C
Explanation
The best answer is Multicast. In enterprise networks, multicast is used for applications such as live audio/video streaming, where a single source needs to send the same content to multiple receivers efficiently. Unlike unicast, which creates a separate stream per receiver, multicast allows one stream to be sent to a multicast group and replicated by the network only where necessary. Unlike broadcast, multicast does not send traffic to every device in the broadcast domain. This aligns with common networking best practices for conserving bandwidth on switched networks. Concepts related to multicast operation are standardized through IETF documentation such as IGMP for IPv4 group membership management and PIM for multicast routing in larger networks. For Network+ purposes: unicast = one-to-one, broadcast = one-to-all on a local subnet, multicast = one-to-many for subscribed receivers, and anycast = one-to-nearest/one-of-many service endpoint.
- A. Incorrect.
Unicast is a one-to-one communication method. If the server sends a separate stream to each of the 120 employees, that is unicast traffic. This is exactly the behavior causing the bandwidth issue in the scenario, so unicast does not solve the problem.
- B. Incorrect.
Broadcast is one-to-all communication within a broadcast domain. While it reaches multiple devices, it sends traffic to every host on the subnet, including devices that did not request the training stream. The scenario specifically requires delivery only to employees who joined the session, so broadcast is inefficient and incorrect.
- C. Correct.
Multicast is the correct answer because it is designed for one-to-many communication where only interested receivers join the multicast group. The server can send a single stream, and the network replicates traffic only where needed for subscribed clients. This reduces unnecessary bandwidth consumption compared to multiple unicast streams and avoids flooding all hosts like a broadcast.
- D. Incorrect.
Anycast is typically used to send client requests to the nearest or best destination among multiple identical service endpoints, such as DNS resolvers or CDN nodes. It is not used to distribute one video stream from one sender to many interested receivers on a LAN in the way described here.