Cyber Fundamentals Block 1 Practice Exam 2026 - Free Cybersecurity Practice Questions and Study Guide

In the OSI model, layers are stacked from bottom to top, with lower layers providing services to the ones above. The Transport layer sits above the Network layer, so the layer directly below Transport is the Network layer. The Network layer handles routing and logical addressing to move packets across multiple networks. Data Link is two levels below Transport and deals with framing and error detection on a single link, so it isn’t directly beneath Transport.