What is a network?
A network connects devices so they can share data. The internet is a huge network of networks.
Key ideas
| Term | Meaning |
|---|---|
| IP address | A device's address on a network, like 192.168.1.10 |
| Router | Connects your network to the internet and directs traffic |
| Switch | Connects wired devices within a network |
| DHCP | Automatically gives devices an IP address |
| DNS | Translates names like example.com into IP addresses |
| Gateway | The router address devices use to reach other networks |
| Wi-Fi | Wireless access to the network |
Public and private IP addresses
Home and office devices use private addresses (for example 192.168.x.x, 10.x.x.x). Your router has one public address facing the internet.
Troubleshooting steps
When a user says "the internet is not working", work from the bottom up:
- Physical: is the Wi-Fi on? Is the cable plugged in? Is the router powered?
- Local network: does the device have an IP address? (
ipconfigon Windows,ip aon Linux) - Gateway: can it reach the router? (
ping 192.168.1.1) - Internet: can it reach the internet by IP? (
ping 8.8.8.8) - DNS: can it resolve names? (
ping google.com,nslookup google.com)
ipconfig /all
ping 192.168.1.1
ping 8.8.8.8
nslookup example.com
tracert example.com # tracert on Windows, traceroute on LinuxWhat the results tell you
- Router works but the internet does not: check the internet connection or ISP.
- IP address works but names do not: DNS problem.
- No IP address (169.254.x.x): DHCP problem.
Wi-Fi tips
- Move closer to the router and reduce obstacles.
- Restart the router and device.
- Use the 5 GHz band for speed and 2.4 GHz for range.
- Use WPA2 or WPA3 security with a strong password.
Practice
Draw your home network with the router, your phone and your laptop, and run the troubleshooting commands on your own computer.