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

In the Differentiated Services (DiffServ) model, Per-Hop Behaviors (PHBs) define how packets are treated as they traverse network nodes based on predefined classes of service. There are indeed five recognized types of PHB, which are designed to support various levels of service differentiations suitable for different types of applications.

The main PHBs include:

1. **Default Forwarding (DF)** PHB, which is the standard forwarding treatment for all traffic that does not match any specific traffic class.

2. **Class Selector PHBs**, which provide differentiated service levels for more specific types of traffic based on defined prioritization.

3. **Expedited Forwarding (EF)** PHB is designed for low-loss, low-latency traffic, typically used for voice or video communications, ensuring a higher quality of service.

4. **Assured Forwarding (AF)** PHB provides four sub-classes of service, each having varying degrees of forwarding assurance with respect to packet loss.

5. **Network-controlled PHBs (such as Multicast)** that can cater to specific network conditions or requirements.

Overall, the five types of PHB enable network operators to apply various treatment models in a scalable manner, allowing for efficient bandwidth utilization and performance optimization