Computer Networks
A comprehensive guide to computer networking concepts, organized by topic.
📚 Topics
Core Concepts
| File | Description |
|---|---|
| OSI & TCP/IP Model | Network layer models (7-layer OSI, 4-layer TCP/IP) |
| IP Addressing | IP types, MAC, Subnetting, CIDR, NAT |
| Transport Protocols | TCP, UDP, Ports |
| Routing | OSPF, BGP, Autonomous Systems, Traceroute |
Application Layer
| File | Description |
|---|---|
| HTTP and Web | HTTP methods, status codes, APIs, URLs, Cookies |
| DNS | Domain Name System, CNAME records |
| Email Protocols | SMTP, POP3, IMAP |
| FTP | File Transfer Protocol |
Security
| File | Description |
|---|---|
| Network Security | Firewall, VPN, Proxy, SSH |
| Encryption & SSL/TLS | SSL, TLS, Public/Private keys |
Services & Infrastructure
| File | Description |
|---|---|
| Network Services | CDN, Load Balancer, DHCP, WebSocket, QoS, MPLS |
Reference
| File | Description |
|---|---|
| Quick Q&A | Common networking questions and answers |
🎯 Quick Reference
Default Ports
| Service | Port |
|---|---|
| HTTP | 80 |
| HTTPS | 443 |
| FTP | 21 |
| SSH | 22 |
| DNS | 53 |
| SMTP | 25 |
| POP3 | 110 |
| IMAP | 143 |
🌐 Networking Protocol Map
flowchart TD
subgraph AppLayer["🌐 Application Layer"]
HTTP["HTTP / HTTPS (Web)"]
DNS["DNS (Name Resolution)"]
Email["SMTP / POP3 / IMAP (Mail)"]
FTP["FTP / SFTP (File Transfer)"]
SSH["SSH (Remote Shell)"]
end
subgraph TransportLayer["🚚 Transport Layer"]
TCP["TCP (Reliable / 3-Way Handshake)"]
UDP["UDP (Fast / Connectionless)"]
end
subgraph InternetLayer["🗺️ Internet / Network Layer"]
IP["IPv4 / IPv6 (Addressing & NAT)"]
Routing["OSPF (IGP) / BGP (EGP)"]
ICMP["ICMP (Ping / Traceroute)"]
end
subgraph LinkLayer["🔌 Network Access / Data Link / Physical"]
Eth["Ethernet / Wi-Fi (MAC Framing)"]
Hardware["Cables / Fiber / NICs / Switches"]
end
HTTP --> TCP
FTP --> TCP
SSH --> TCP
Email --> TCP
DNS --> UDP
DNS --> TCP
TCP --> IP
UDP --> IP
Routing --> IP
ICMP --> IP
IP --> Eth --> Hardware