Introduction To Networking

What is Networking?

Computer Networking is the practice of connecting computers and devices to share resources and exchange data. Networking covers everything from the physical cabling and radios to protocols and application-level services that run over those links.

Networking enables the Internet and every distributed system — understanding it is crucial for building reliable, fast, and secure systems.

┌─────────────────────────────────────────────────────────────────┐
│                           Networking Stack                      │
├─────────────────────────────────────────────────────────────────┤
│ Application │ Transport (TCP/UDP) │ Network (IP) │ Link (Ethernet/Wi‑Fi) │
└─────────────────────────────────────────────────────────────────┘

Why Learn Networking?

• Performance: Latency and bandwidth directly impact application UX.
• Reliability: Network partitions and failures are common — design to tolerate them.
• Security: Many attacks exploit networking — secure protocols and proper configuration matter.

What We'll Cover

From fundamentals to real-world patterns:

Fundamentals

Building Blocks

Advanced Topics

Real-World Examples

Prerequisites

┌─────────────────────────────────────────────────────────────────┐
│                    Recommended Background                       │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  ✓ Basic TCP/IP familiarity                                      │
│  ✓ Comfort with command line tools (curl, netstat, tcpdump)     │
│  ✓ Understanding of HTTP and APIs                                │
│                                                                 │
│  Nice to have:                                                  │
│  ○ Experience with cloud networking (VPCs, subnets)             │
│  ○ Familiarity with TLS and certificates                        │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

Networking Mindset

1. Measure First

Don't guess; measure latency, bandwidth, packet loss, and retries. Use tools (ping, iperf, tcpdump) to gather data.

2. Think in Layers

Design at the appropriate layer — don't reinvent transport-level concerns at the application layer.

3. Design for Failure Modes

Networks fail in well-known ways: partitions, congestion, blackholing. Use retries with backoff, idempotency, and circuit breakers.

Important Numbers & Rules of Thumb

Key Concepts (Illustrative)

TCP vs UDP

Load Balancer Patterns

Clients ─► LB ─► App Pool
		  └─ health checks

Consider session affinity only when necessary; prefer stateless services with shared storage or sticky cookies carefully.

DNS Best Practices

• Keep TTLs moderate: low TTL for services that move often, higher TTL for stable records.
• Use multiple authoritative name servers across providers/regions.

Security

• Use TLS everywhere (HTTPS, mTLS for service-to-service).
• Validate certificates and pin where appropriate.
• Rate-limit and filter suspicious traffic at the edge.

Troubleshooting & Tools

How to Use This Documentation

1. Start with the transport and addressing sections.
2. Practice with packet captures and simulated failures.
3. Build small services and measure the effect of changes (keep/tear down connections, change congestion windows).

Key Takeaways

┌─────────────────────────────────────────────────────────────────┐
│                        Networking Principles                    │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  1. Measure before optimizing                                    │
│  2. Failures are common — design resilience                       │
│  3. Use the right layer for the right problem                    │
│  4. Secure the transport and endpoints                           │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

Next Steps

1. Transport & Protocols — Deep dive into TCP, UDP, QUIC
2. DNS & Service Discovery — Name resolution and discovery patterns
3. Load Balancing & CDNs — Edge delivery and traffic distribution

Happy networking — the Internet is your playground!