Summary

What is Network

A computer network is a group of interconnected computers that communications to share resources.

Hardware

• Network Interface Card (NIC)
• Ethernet cable
• Switch
• Hub
• Rounter
• Modem

OSI (Open Systems Interconnection)

• Physical layer (1)
• Data link layer (2)
• Network layer (3)
• Transport layer (4)
• Session layer (5)
• Presentation layer (6)
• Application layer (7)

Example TCP-IP

• Your web browser (Layer 7) makes a request (HTTP).
• Data formatted & encrypted (Layer 6) → session managed (Layer 5).
• Transport Layer decides TCP (Layer 4).
• IP address routing decision (Layer 3) → MAC addresses for local delivery (Layer 2).
• Data travels as electrical signals over a cable (Layer 1).
• Goes through switches → router → internet → destination server.
• Response comes back in reverse order!