(ISC)2 Certified in Cybersecurity Practice Exam

What does Layer 3 of the OSI model represent?

1. Bit

2. Frame

3. Packet

4. Segment

The correct answer is: Packet

Layer 3 of the OSI (Open Systems Interconnection) model is known as the Network Layer. This layer is primarily responsible for the delivery of packets from the source host to the destination host across multiple networks. It provides routing, forwarding, and addressing functions to ensure that data is transmitted efficiently across different routes. The term "Packet" specifically refers to the data unit that Layer 3 handles. When data is encapsulated for transmission, it progresses through several layers, with each layer adding its own header information. At the Network Layer, the data is encapsulated into packets, which include source and destination IP addresses, allowing the data to traverse across different networks to reach its intended destination. In contrast, the other terms listed pertain to different layers of the OSI model. A "Bit" refers to the physical Layer (Layer 1) that deals with the transmission and reception of raw binary data over a physical medium. A "Frame" is associated with Layer 2, the Data Link Layer, which is concerned with node-to-node data transfer and includes headers that enable devices on the same local area network (LAN) to identify each other. A "Segment" is related to Layer 4, the Transport Layer, which is responsible for