Follow one web request from a client to a server, one layer at a time.
Networks send data by wrapping it in layers. Each layer adds its own header, like putting an addressed envelope inside another envelope. The OSI model describes seven layers and the TCP/IP model describes four. This lab follows one web request down the client’s layers, across the network and up the server’s layers.
Why it matters. When something breaks, knowing which layer is failing tells you where to look: the cable, the switch, the IP address, the port or the application.
How to use this lab. Press Next to step through. Switch between the OSI and TCP/IP views, and try the Break it scenarios to see which layer drops the packet.
Where it fits. Start here. Every other lab builds on these layers. It pairs with the Frame Inspector, which shows the real bytes.