Network — Infrastructure & Protocols Training
Last reviewed: 2026-05-29
Computer networking is the practice of connecting computers and devices to share resources, communicate, and exchange data. This training covers foundational networking concepts, protocols, hardware, and practical configuration.
Overview
Modern networks form the backbone of every digital service — from the internet to private enterprise networks and cloud infrastructure. Understanding networking is essential for systems engineers, DevOps practitioners, and backend developers.
Core Networking Concepts
OSI Model (7 Layers)
| Layer |
Name |
Examples |
| 7 |
Application |
HTTP, FTP, SMTP, DNS |
| 6 |
Presentation |
TLS/SSL, JPEG, encryption |
| 5 |
Session |
NetBIOS, RPC, session management |
| 4 |
Transport |
TCP, UDP |
| 3 |
Network |
IP, ICMP, routing protocols |
| 2 |
Data Link |
Ethernet, Wi-Fi, ARP, MAC |
| 1 |
Physical |
Cables, fiber, radio, voltage |
TCP/IP Model (4 Layers)
| Layer |
Equivalent OSI |
Protocols |
| Application |
5–7 |
HTTP, DNS, SSH, SMTP |
| Transport |
4 |
TCP, UDP |
| Internet |
3 |
IP, ICMP, ARP |
| Link |
1–2 |
Ethernet, Wi-Fi, PPP |
Common Protocols
| Protocol |
Purpose |
Port |
| HTTP |
Web browsing |
80 |
| HTTPS |
Secure web |
443 |
| DNS |
Name resolution |
53 |
| DHCP |
IP address assignment |
67/68 |
| SSH |
Secure remote shell |
22 |
| SMTP |
Email sending |
25 |
| FTP |
File transfer |
21 |
Network Devices
| Device |
OSI Layer |
Function |
| Hub |
1 (Physical) |
Broadcast all traffic to all ports |
| Switch |
2 (Data Link) |
Forward frames based on MAC addresses |
| Router |
3 (Network) |
Route packets between networks |
| Firewall |
3–7 |
Filter traffic based on rules |
| Load Balancer |
4/7 |
Distribute traffic across servers |
| Access Point |
1/2 |
Wireless connectivity |
IP Addressing
IPv4
- Format: 32-bit, dotted decimal (e.g.,
192.168.1.1)
- Classes: A (1–126), B (128–191), C (192–223), D (Multicast), E (Reserved)
- Private ranges:
10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
- CIDR notation:
192.168.1.0/24 → 256 addresses, 254 usable
IPv6
- Format: 128-bit, hexadecimal (e.g.,
2001:db8::1)
- No NAT needed — enough addresses for every device
- Prefix notation:
2001:db8::/32
- Link-local:
fe80::/10 — auto-configured per interface
Key Networking Tasks
# DNS lookup
nslookup example.com
dig example.com
# Network connectivity test
ping -c 5 8.8.8.8
# Trace route
traceroute google.com # Linux
tracert google.com # Windows
# Show open ports
netstat -tulpn # Linux
ss -tulpn # Modern Linux
# Capture traffic
tcpdump -i eth0 port 443
tshark -i eth0 # Wireshark CLI
Resources