Networking - The Backbone of the Internet

Networking basics for beginners

Index

1. Client-Server Architecture
2. Ports
3. Network Protocols - TCP, UDP, HTTP, FTP, Packets
4. IP Address, DNS, DHCP, NAT
5. Internet Speed
6. Physical Communication Media
7. Wireless Communication
8. Types of Networks
9. Optical Fibre Technologies
10. Modem & Router
11. ISP Tiers
12. Network Topologies

Client-Server Architecture

A model where:

• Client requests services/resources
• Server responds with data/services

Examples

• Browser → Web Server
• Mobile App → API Server
• Frontend → Backend → Database

Important points

• Clients initiate communication
• Servers listen continuously for requests
• One server can handle multiple clients simultaneously
• Communication happens over networks using protocols

Flow

User → Browser → Internet → Server → Database

Why it matters

• Foundation of modern web applications
• Enables scalability and centralized data management

Ports

• A logical communication endpoint in networking
• Helps identify which service/application should receive data

Example

• IP Address = Building Address
• Port = Apartment Number

• Ports have 16 bits
  • Total = 2^16 ~ 65000

Important points

• Ports range from 0–65535
• One IP can run multiple services using different ports
• Servers “listen” on specific ports

Network Protocols

• Protocol -> A set of rules for communication between devices

1. TCP - Transmission Control Protocol

• Connection-oriented
• Reliable
• Ordered delivery
• Error checking

Used In

• HTTP/HTTPS
• Email
• File transfers

Important

• Slower but reliable

2. UDP - User Datagram Protocol

• Connectionless
• Faster
• No delivery guarantee

Used In

• Video streaming
• Gaming
• Voice calls

Important

• Faster but less reliable

3. HTTP - HyperText Transfer Protocol

• Transfers web pages and API data
• HTTP usually works on top of TCP

Important

• Stateless protocol

4. FTP - File Transfer Protocol

• Transfers files between systems

Important

• Older protocol, less secure than SFTP/HTTPS

5. Packets - Not a Protocol

• Small chunks of data sent across networks

Important points

• Large data is broken into packets
• Each packet contains:
  • Source IP
  • Destination IP
  • Actual data
• Routers forward packets toward their destination

Why it matters

• Efficient data transfer over the internet

IP Address, DNS, DHCP, NAT

1. IP Address

• Unique identifier for a device on a network

Types

• IPv4 → 192.168.1.1
• IPv6 → Longer modern format

Important Points

• Public IP → Internet-facing
• Private IP → Internal network
• IP Address of device is same for all applications but ports identifies which app have requested the service

2. DNS - Domain Name System

• Converts domain names into IP addresses

Example

google.com → 142.250.x.x

why it's Important

Humans already forget why they opened the fridge at night, remembering IP addresses for every website would be impossible.

Simple flow

Browser → DNS → IP Address → Server

3. DHCP - Dynamic Host Configuration Protocol

• Automatically assigns IP addresses to devices

IP1, IP2, IP3 ↓ Local IP Address ↓ Assigned using DHCP

Important Points

• Saves manual configuration
• Common in WiFi routers

Example

When you connect to WiFi:

• Router gives:
  • IP Address
  • Gateway
  • DNS Server

4. NAT - Network Address Translation

• Allows multiple devices to share one public IP
• Decides which device has requested

Important Points

• Used in home routers
• Improves IP conservation and security

Example

10 devices at home → 1 public IP

Every website, app, API, and cloud service ultimately depends on these core networking concepts working together behind the scenes.

**These topics will be covered deeply in future blogs too. This was just a glimpse of why networking is important in today's world.

Internet Speed

Internet speed is not always exactly what your ISP advertises. For example, a 100 Mbps connection may give lower real-world speed depending on:

• Number of connected devices
• Router location and signal strength
• Network congestion
• Wi-Fi vs Ethernet connection
• Device capability
• Website/server speed

Speed Units

1 Kbps = 10³ bits/s
1 Mbps = 10⁶ bits/s
1 Gbps = 10⁹ bits/s

Important Difference

Internet providers measure speed in bits, while file sizes are measured in Bytes.

1 Byte = 8 bits

So a 100 Mbps connection gives a maximum practical download speed of around:

100 ÷ 8 = 12.5 MB/s

Latency (Ping)

• Speed → How much data transfers per second
• Latency → How fast data travels between devices

Low latency is important for:

• Gaming
• Video calls
• Real-time applications

A fast internet plan alone does not guarantee fast performance — network quality and latency matter too.

Physical Communication Media

1. Optical Fibre Cables

• Uses light signals to transmit data
• Made of glass/plastic fibers

Important Points

• Extremely high speed
• Long-distance communication
• Low signal loss
• Immune to electromagnetic interference

Used in

• Internet backbone
• Data centers
• Undersea cables
• Telecom networks

2. Coaxial Cables

• Copper cable with insulation and shielding

Important Points

• Better shielding than twisted pair cables
• Used for TV and broadband internet
• More durable against signal interference

Used in

• Cable TV
• Broadband connections
• CCTV systems

Wireless Communication

1. Wi-Fi

• Wireless local area networking technology

Important Points

• Uses radio waves
• Limited range
• Common for homes/offices
• Works through routers/access points

Standards

• Wi-Fi 4, 5, 6, 6E, 7

2. Bluetooth

• Short-range wireless communication

Important Points

• Low power consumption
• Used for device-to-device communication
• Ideal for accessories

Examples

• Earbuds
• Smartwatches
• Wireless keyboards

3. Mobile Network Generations

2G

• Introduced digital voice communication
• SMS support
• Very slow internet

3G

• Mobile internet became practical
• Video calling support
• Faster than 2G

LTE (4G)

• LTE = Long Term Evolution

Features

• High-speed mobile internet
• HD streaming
• Low latency
• Mostly data-focused network

VoLTE

• VoLTE = Voice over LTE

Features

• Voice calls over 4G network
• Better call quality
• Faster call connection

5G

Features

• Extremely high speed
• Very low latency
• Supports IoT and smart devices

Applications

• Self-driving cars
• Smart cities
• AR/VR
• Remote surgery

Types of Networks

1. LAN (Local Area Network)

Features

• Small geographic area
• High speed
• Privately owned

Examples

• Home Wi-Fi
• Office network

2. MAN (Metropolitan Area Network)

Features

• Covers a city or campus
• Larger than LAN

Examples

• City-wide internet network
• University campuses

3. WAN (Wide Area Network)

Features

• Covers very large areas/countries
• Connects multiple LANs/MANs

Example

• The Internet

Optical Fibre Technologies

1. SONET

• SONET = Synchronous Optical Network

Purpose

• Standard for high-speed optical communication

Important Points

• Uses fiber optics
• Highly reliable
• Used by telecom providers

2. Frame Relay

What it is

• Older WAN technology for packet switching

Important Points

• Faster than traditional leased lines
• Less expensive historically
• Mostly replaced by MPLS and modern networks

Modem and Router

1. Modem

Purpose

• Converts digital ↔ analog signals

Important Points

• Connects home network to ISP
• “Modulator-Demodulator”

2. Router

Purpose

• Routes data between networks

Important Points

• Assigns local IP addresses
• Connects multiple devices
• Often includes Wi-Fi functionality

ISP Tiers

1. Tier 1 ISP

Features

• Owns global internet backbone
• No need to pay for transit

Examples

• Large global telecom companies

Important Point

• Highest level internet providers

2. Tier 2 ISP

Features

• Buys internet transit from Tier 1
• Provides regional services

Important Point

• Connects businesses and consumers

Network Topologies

1. Bus Topology

Features

• Single backbone cable
• All devices connected to same cable

Pros

• Cheap
• Simple

Cons

• Backbone failure affects entire network

2. Ring Topology

Features

• Devices connected in circular form

Important Point

• Data travels around the ring

Cons

• One failure can disrupt network

3. Star Topology

Features

• All devices connected to central hub/switch

Pros

• Easy management
• Most common modern topology

Cons

• Hub failure affects network

4. Tree Topology

Features

• Hierarchical structure
• Combination of star and bus

Used in

• Large organizations

5. Mesh Topology

Features

• Devices interconnected directly

Pros

• Very reliable
• Redundant paths

Cons

• Expensive
• Complex setup

Used in

• Military
• Data centers
• Critical infrastructure

Modern networking combines physical infrastructure, wireless communication, protocols, and intelligent routing to keep the digital world connected 24/7.

What I Learned

• Every internet communication depends on protocols
• Ports help services communicate properly
• DNS makes the internet human-friendly
• TCP and UDP solve different problems
• Networking is the foundation of backend and distributed systems