Quick Network Review 2025

🌐 Networking Basics

• Network: Devices connected to share data
• Types: LAN, WAN, MAN, WLAN
• Topologies: Star, Bus, Ring, Mesh

🔢 IP Addressing

IPv4

• 32-bit, decimal
• Example: 192.168.1.1
• Private ranges:
• 10.0.0.0/8
• 172.16.0.0/12
• 192.168.0.0/16

IPv6

• 128-bit, hexadecimal
• Example: 2001:db8::1
• No broadcast, uses multicast

🎭 OSI Model (Must Know)

1. Physical
2. Data Link
3. Network
4. Transport
5. Session
6. Presentation
7. Application

📌 IP → Layer 3, TCP/UDP → Layer 4

🚦 TCP vs UDP

TCPUDPReliableFastConnection-orientedConnectionlessUses handshakeNo handshake

🧰 Common Protocols

• HTTP – Web
• HTTPS – Secure web
• FTP – File transfer
• SMTP – Send email
• POP3 / IMAP – Receive email
• DNS – Name to IP
• DHCP – Auto IP

🔌 Devices

• Hub – Broadcast
• Switch – MAC address
• Router – IP address
• Firewall – Security

🔁 Routing & Switching

• Static Routing – Manual
• Dynamic Routing – OSPF, RIP, BGP
• VLAN – Logical network separation

🔐 Security Basics

• Firewall
• NAT
• VPN
• ACL

🧪 Troubleshooting Tools

• ping
• tracert / traceroute
• ipconfig / ifconfig
• netstat

🎯 Interview One-Line Facts

• IPv6 has no broadcast
• Switch works at Layer 2
• Router works at Layer 3
• DNS converts name → IP
• DHCP gives IP automatically

If you want, I can send:

• ✅ 1-page PDF revision sheet
• ✅ Interview MCQs
• ✅ CCNA / Juniper quick notes