Free tools · Networking
OSI layer matcher
Ten devices, protocols and data units. Pick the layer. The stack highlights the answer and explains why it belongs there.
Which layer?
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Questions
You need the order and the job of each layer. Exams rarely ask for a definition in isolation. They show a device, a protocol data unit or a troubleshooting symptom and ask which layer it belongs to. Practice the mapping: cable at 1, frame and MAC at 2, packet and IP at 3, segment and ports at 4, then the application-facing layers.
Layer questions are troubleshooting questions in disguise
A cable fault, a VLAN mismatch, a missing route and a blocked port all look similar from the help desk. SecLern labs teach you to name the layer before you change a setting.
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