Part 2 · Lesson 7 · Intermediate

Packets & Routing

Follow a packet hop by hop across the internet.

In this interactive Infrastructure lesson from Stencel Academy you don't just read — you type real commands like traceroute api.stencel.ai, ping -c 3 api.stencel.ai and watch the machine respond on a live, animated map. It is part of the free How Infrastructure Works course.

Key takeaway: There is no direct wire — every packet is handed router to router, and each hop adds latency.

Before this lesson

Builds on: Addresses & Networks.

What you'll practise

ping -t 2 -c 1 api.stencel.ai — Cap the TTL yourself — hop 2 answers instead.
traceroute -n api.stencel.ai — Skip reverse DNS: just the addresses, faster.
mtr -rwc 1 api.stencel.ai — traceroute + ping, continuously, with loss per hop.
ip route get 203.0.113.10 — The only routing decision your laptop makes.

Terms you'll learn

routerhopTTLlatencyinternet exchange

Check your understanding

How does traceroute discover each router on the path?

It sends packets with rising TTLs; each router where TTL expires replies
Routers publish a public list of every path
It asks DNS for the route to the server

Open the interactive lesson →