Network: Devices connected to share data
Internet vs Intranet
LAN / WAN / WLAN
Bandwidth vs Latency
Router – connects networks (internet access)
Switch – connects devices within a LAN
Access Point – provides Wi-Fi
Modem – connects to ISP
Physical
Data Link
Network
Transport
Session
Presentation
Application
👉 Memory trick: Please Do Not Throw Sausage Pizza Away
Network Access
Internet
Transport
Application
32-bit address (e.g., 192.168.1.1)
Classes (basic knowledge):
Class A: 1–126
Class B: 128–191
Class C: 192–223
Split networks into smaller parts
Know:
Subnet mask (e.g., 255.255.255.0)
CIDR notation (e.g., /24)
👉 Example:
/24 = 255.255.255.0 = 256 addresses
HTTP (Web)
HTTPS (Secure web)
FTP (File transfer)
DNS (Name → IP)
DHCP (Auto IP assignment)
SMTP/POP3/IMAP (Email)
HTTP → 80
HTTPS → 443
FTP → 21
DNS → 53
SSH → 22
DHCP: Assigns IP automatically
DNS: Translates domain names
NAT: Private → Public IP translation
Wi-Fi standards (802.11 a/b/g/n/ac/ax)
Frequencies:
2.4 GHz (longer range)
5 GHz (faster, shorter range)
WEP (weak ❌)
WPA / WPA2 / WPA3 (secure ✅)
Firewall – filters traffic
VPN – secure remote connection
Antivirus / Anti-malware
Phishing
Malware
DDoS attacks
Identify the problem
Establish theory
Test theory
Fix issue
Verify
Document
ping – tests connectivity
ipconfig / ifconfig – IP info
tracert – path to destination
Ethernet (Cat5e, Cat6)
Fiber optic
Coaxial
Cloud types:
Public
Private
Hybrid
Virtual machines (VMs)
Practice subnetting daily
Memorize ports & protocols
Understand (not just memorize) OSI layers
Use flashcards for quick recall
Take practice tests (you mentioned 75-question sets — great idea)