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Session and Presentation

Lesson 21 of 32 in Coddy's The OSI Model course.

Layers 5 and 6 are the strangest part of the OSI model, because modern software rarely implements them as separate pieces. In OSI theory:

Layer 5, Session: opens, manages and closes dialogs, so a long conversation can resume instead of restart.
Layer 6, Presentation: translates formats so both sides understand the bytes: character encodings, compression, and encryption.

In practice, TLS handles encryption and applications manage their own sessions. But interview questions and certification exams still ask for the theory placement, so learn it: dialogs at 5, encryption at 6.

Challenge

Beginner

Print the OSI layer number responsible for each job, one per line:

Encrypting data (in OSI theory)
Managing dialogs between machines

Expected output:

6
5

Try it yourself

Terminal

All lessons in The OSI Model

1Why Layers

The Layering Idea Seven Layers Numbers and Names Recap - The Stack

4The Network Layer

IP and TTL Ping and ICMP Routing Tables Recap - Layer Three

7Encapsulation

Wrapping Data Headers Everywhere Reading a Capture Recap - Follow the Wrap

2The Physical Layer

Bits on a Wire How Long Will It Take Duplex and Collisions

5Transport: TCP and UDP

Ports The TCP Handshake TCP vs UDP Sockets in Action Recap - Layer Four

8The Journey of a Packet

A Click Happens Crossing the Networks Arriving and Climbing Recap - End to End

3Data Link and MACs

Frames and MACs Reading a MAC ARP Recap - Layer Two

6The Upper Layers

Session and PresentationThe Application Layer Watching the Layers Recap - Top of the Stack

Practice on your own: Terminal playground