The idea

A laptop at home, the home router (its way out, which also looks up names), and a web server on another network. Follow one request from the laptop to the server, one piece at a time: this home network lab runs on real Linux machines.

Not on my network: hand it to the router

Steps

Where the laptop is

Every device on a network has a number, like a street address, so that packets for it know where to go. Before the laptop can talk to anyone, it needs its own. Ask the laptop for it.
```
laptop:~# ip -4 addr show eth0
```
The way out

The web server, 10.0.2.10, is outside the laptop's 10.0.1. network, and the laptop can only reach its own network directly. So it needs one place to hand everything else to. Read where the laptop sends packets.
```
laptop:~# ip route
```
Names become addresses

People type names like webServer.lab, but every packet carries an address, so a name must become an address before anything is sent. Ask for the address behind the name.
```
laptop:~# dig +short webServer.lab
```
Talk to the server

You have the address and the way there; a browser does exactly this next. Ask the web server for its page over HTTP, the language of web pages.
```
laptop:~# curl -s http://webServer.lab
```
The router hides the laptop

The laptop's 10.0.1.10 is a private address: the internet never sends replies to it. So who does the server see? Fetch the page again while the server records what reaches it.
```
laptop:~# curl -s http://webServer.lab
```
A server goes down

Servers go down, and the symptom tells you where to look. The lab turns the web server off; ask for its name and its page, then it comes back on.
```
laptop:~# dig +short webServer.lab
laptop:~# curl -sS -m 5 http://webServer.lab
laptop:~# curl -s http://webServer.lab
```

Run these steps on real machines

A home network, from the laptop's point of view

The idea

Steps

Where the laptop is

The way out

Names become addresses

Talk to the server

The router hides the laptop

A server goes down

Learn it on real machines.