Part 2 · Lesson 6 · Intermediate

Addresses & Networks

Two addresses, one laptop: private inside, public at the edge.

In this interactive Infrastructure lesson from Stencel Academy you don't just read — you type real commands like ip addr, curl ifconfig.me and watch the machine respond on a live, animated map. It is part of the free How Infrastructure Works course.

Key takeaway: Your private address works only at home; NAT lets one public address speak for the whole network.

Before this lesson

Builds on: APIs, JSON & Tokens.

What you'll practise

ip route — Every non-local packet goes to the gateway.
ip -brief addr — The same answer, one line per interface.
ip neigh — Your LAN neighbours, resolved to MAC addresses.
ping -c 1 192.168.1.1 — One hop away: sub-millisecond.

Terms you'll learn

IP addressprivate addresspublic addressNATsubnet (CIDR)

Check your understanding

ip addr says 192.168.1.42 but ifconfig.me says 84.12.7.90 — why?

NAT: the router swaps your private address for its public one
The website is broken — both should match
Your laptop has two network cards

Open the interactive lesson →