Interview Q&A / Computer Networks

1. What does each of the seven OSI layers do, in one line each?

   Physical sends bits, Data Link moves frames between neighbours, Network routes packets across networks, Transport delivers data between processes, Session manages dialogues, Presentation handles format and encryption, Application is what the user's software talks to.

   BeginnerQuick answer1 min read
2. What is encapsulation, and what is the data unit called at each layer?

   Encapsulation means each layer wraps the data from the layer above with its own header. The unit is called data at the application layer, a segment (TCP) or datagram (UDP) at transport, a packet at network, a frame at data link, and bits at physical.

   BeginnerQuick answer1 min read
3. At which OSI layer does TLS work?

   TLS has no clean place in OSI. It runs on top of TCP and below HTTP, so it is usually described as layer 6 (presentation) or between layers 4 and 7. In the TCP/IP model it simply sits inside the application layer.

   IntermediateQuick answer1 min read