Software-Defined Networking

Correct Answer: SD-WAN

The best software-defined networking (SDN) solution to optimize network traffic between two congested locations would be SD-WAN (Software-Defined Wide Area Network). SD-WAN simplifies the management and operation of a WAN by decoupling the networking hardware from its control mechanism. It can prioritize traffic, ensure optimal delivery of network services and increase network efficiency. ACL (Access Control List) is not the optimal solution here because it is a set of rules used to control network traffic and reduce network attacks. It doesn't optimize network traffic. Sflow and MPLS (Multiprotocol Label Switching), on the other hand, are technologies used in network monitoring and creating virtual private networks respectively, not particularly used for traffic optimization between locations.

Correct Answer: Quality of Service (QoS)

The best answer is 'Quality of Service (QoS)'. Quality of Service is a feature of SDN that allows for the prioritization of certain types of traffic over others based on application requirements. This feature ensures that critical services get the resources they need first. In contrast, 'Policy-based routing' is a method of forwarding networks based on set policies, but it does not inherently prioritize certain types of traffic over others based on application needs. 'Round-robin routing' is a method used to distribute network traffic evenly over several servers or resources but doesn't accommodate priority-based distribution. Finally, 'Broadcast storm prevention' is a method of preventing a network failure due to excessive broadcast/multicast traffic, which doesn't have a direct correlation to the prioritization of certain traffic types over others.

Correct Answer: Controller

In a software-defined network (SDN), the component responsible for providing the northbound API, enabling communication and integration with other network elements such as applications and orchestration tools is the 'Controller'. The Controller is the core of a SDN network. It provides the centralised logic that controls the behaviour of the whole network. Switch, Router, and Firewall cannot provide a northbound API as they don't have the responsibility or capability to communicate and integrate with other network elements. These components focus more on data plane operations, sending and receiving data packets, but do not provide the network-wide intelligence that the controller does.