Packets, Ports and Protocols
beginner 45 min 3 tasks
How data really travels: packets, the two main delivery styles (TCP and UDP), private address ranges, and the ports you will see everywhere.
By the end of this lesson you can explain what a packet is, tell TCP from UDP, describe the three-step TCP handshake, recognise private address ranges and subnets, and name the service behind the most common ports. This lesson has no lab and no commands to run: it builds the picture of a network that every later lesson uses, and every answer is in the text.
Part of these paths
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Updated 2026-11-01