A computer network connects devices (computers, servers, printers, phones) so they can exchange data and share resources. Without a network, every machine would sit isolated.

What a network makes possible

• Sharing files, printers and an Internet connection.
• Communicating (email, voice over IP, video conferencing).
• Centralising applications and data on servers.

Networks are classified by their reach: the LAN (local area network, a single building), the WAN (wide area network, between remote sites) and the Internet, the network of networks. Every host is identified by an IP address and a MAC address.

To explore a network you use a few basic commands on a PC. Here are some you will meet in the very first lab.

C:> ipconfig
C:> ping 192.168.1.1
C:> tracert 8.8.8.8

These tools confirm that a host has an address and that it can reach its neighbours. They are the foundation of network troubleshooting.

Key point: a network exists to share resources and communications. Every host has a unique IP address. See Lab 0 – Exploring a network in Packet Tracer.