CCNA Notes for Beginners

CCNA Notes for Beginners

What is Networking?

Networking is the practice of connecting computers and devices so they can share data and resources.

Common network types:

LAN – Local Area Network

WAN – Wide Area Network

MAN – Metropolitan Area Network

PAN – Personal Area Network

OSI Model (7 Layers)

The OSI model explains how data travels across a network.

Physical – Cables, signals, hardware

Data Link – MAC addresses, switches

Network – IP addressing, routing

Transport – TCP/UDP, ports

Session – Session management

Presentation – Encryption, compression

Application – User-facing services (HTTP, FTP, DNS)

Remember: Please Do Not Throw Sausage Pizza Away

TCP vs UDP

TCP UDP

Reliable Fast

Connection-oriented Connectionless

Error checking No error recovery

Used by HTTP, FTP, SMTP Used by DNS, VoIP, Streaming

IP Addressing

IPv4 – 32-bit (e.g., 192.168.1.1)

IPv6 – 128-bit (used to solve IP exhaustion)

Private IP ranges:

10.0.0.0 – 10.255.255.255

172.16.0.0 – 172.31.255.255

192.168.0.0 – 192.168.255.255

Subnetting (Basic Idea)

Subnetting divides a large network into smaller networks.

Benefits:

Better performance

Improved security

Efficient IP usage

Example:

192.168.1.0/24 = 256 IPs (254 usable)

Networking Devices

Hub – Broadcasts to all devices (obsolete)

Switch – Uses MAC addresses (Layer 2)

Router – Uses IP addresses (Layer 3)

Firewall – Controls traffic using rules