# Computer Networks — Roadmap & Important Topics

> **Quick Revision:** https://www.geeksforgeeks.org/last-minute-notes-computer-network/

## Important Topics

### Models
- OSI Model and TCP/IP Model along with their comparison
  *(Easy explanation: https://www.youtube.com/watch?v=vv4y_uOneC0)*

### Fundamentals
- Common terms: Client, Server, Host, Peer, Packet, Noise, etc.
- Difference between hub, switch and router
- Layers in OSI model and packet transmission **[Very IMP]**
- LAN vs MAN vs WAN
- What happens when you type a URL in the web browser?

### Protocols & Security
- Difference between HTTP and HTTPS
- SSL/TLS + Handshaking algorithm
- What is DHCP and how does it work
- What is ARP and how does it work
- Working of SMTP protocol
- Common networking commands: `telnet`, `ltp`, `ipconfig`, `ping`, `netstat`, `route`, `arp`, `hostname`, `ftp`, `tracert` **[IMP]**

### APIs & Architecture
- How APIs work + API Gateway
- REST API vs HTTP API
- Difference between IPv4 and IPv6

### DNS & IP Addressing
- Explain DNS — concept clarity + associated terms **[V.V.IMP]**
- IP Addresses — difference between public and private IP addresses
- Virtual IP
- Working of server-side Load Balancer

### Cryptography
- Cryptography and encryption methods
- Symmetric vs Asymmetric key
- Hashing and types: AES, DES, RSA, MD5

### File Transfer
- File Transfer Protocol (difference between FTP and Secure FTP)

### System Design Related
- Caching, scaling (horizontal vs vertical)
- Containerisation vs virtualisation
- 2G vs 3G vs 4G vs 5G
- Modem vs Router

### Security
- DDoS Attacks
- Firewalls + Types of firewalls
- Firewall attacks
- Possible network attacks + types
- Network connections: Bluetooth, Hotspot, GPS (basic idea)

## Interview Practice

- **Last-minute revision:** https://www.geeksforgeeks.org/last-minute-notes-computer-network/
- **Important CN interview questions:** https://tushars.xyz/data/cn.html
- **Company-wise problem set:** https://practice.geeksforgeeks.org/tag-page.php?tag=Computer%20Networks#subjectiveProblemDiv
- **Commonly asked CN questions (GFG):** https://www.geeksforgeeks.org/commonly-asked-computer-networks-interview-questions-set-1/

> Also practice numerical-based questions for computer networks — these are commonly asked as MCQs in Round 1 (Coding Test).