Cisco ENCOR Practice Exam 2025 – All-in-One Comprehensive Guide to Mastering Enterprise Network Core Technologies!

The correct choice is IntServ, which stands for Integrated Services. This QoS model is designed to provide guaranteed service quality by reserving resources along the path of the data flow. Before any data transmission occurs, a request (or reservation) must be sent to the network. This reservation allocates the necessary bandwidth and other resources for a flow, ensuring the traffic will receive the required level of service. This characteristic is essential for applications that need a reliable and consistent level of performance, such as voice over IP or video conferencing.

In contrast, Best Effort does not involve any request for resources; the network treats all traffic equally and delivers it as best as it can, without guarantees. DiffServ, which stands for Differentiated Services, classifies and manages network traffic by assigning different levels of priority, but it does not require explicit resource reservation. CSMA/CD is a collision detection protocol used in Ethernet networks and is not related to QoS models, as it deals with how devices on the same physical medium avoid and resolve collisions rather than managing the quality of service for traffic flows.