CREST Practitioner Security Analyst (CPSA) Practice 2025 - Free CPSA Practice Questions and Study Guide

In the OSI model, the Protocol Data Unit (PDU) referred to as a packet is associated with the network layer. The network layer is responsible for the logical addressing and routing of data packets between devices across interconnected networks. It manages how data is sent from the source to the destination using IP addresses as identifiers for each device, allowing for efficient data transmission over diverse networks.

At the network layer, data is encapsulated into packets which contain not only the payload (the actual data being transmitted) but also the necessary headers that provide critical information for routing. This is distinct from other layers: at the transport layer, the PDU is called a segment (or datagram in the case of connectionless protocols like UDP), while at the data link layer, the PDU is termed a frame.

Understanding the role of the network layer and its packets is essential for grasping how data traverses the complex architecture of networking, making it a fundamental concept in networking education and practices.