Networking Basics For DevOps

🌐 How Does the Internet Work?

  • πŸ“± You use a device (phone, laptop) to open a website or app
    Example: You type www.google.com

  • πŸ“‘ Your device sends a request through Wi-Fi or mobile data

  • 🌍 The request travels through networks (routers, internet cables)

  • πŸ–₯️ It reaches a server where the website or app lives
    Example: Google’s server finds your search result

  • πŸ“¦ The server sends data back (like a reply letter)

  • πŸ–₯️ You see the result on your screen
    Example: Google shows your search results!

🌐 3 Tiers of the Internet


πŸ—οΈ Tier 1 – The Internet Builders
They own the global internet backbone (undersea + land cables) and connect networks without paying anyone.
πŸ”Ή E.g., Tata Comm, AT&T, Lumen
πŸ’‘ They’re the highways of the internet.


🚚 Tier 2 – The Distributors
They rent access from Tier 1 to distribute internet across cities and countries, connecting ISPs.
πŸ”Ή E.g., BSNL, Airtel, Jio core
πŸ’‘ They’re trucks using highways to deliver between cities.


🏠 Tier 3 – The Last-Mile Providers
They buy bandwidth from Tier 2 and deliver it to homes/offices via local infrastructure.
πŸ”Ή E.g., JioFiber, Airtel Xstream, ACT
πŸ’‘ They’re the delivery guys bringing internet to your door.


πŸ•ΈοΈ Types of Networks

  • LAN (Local Area Network) 🏠
    A small network in a home or office.
    πŸ”Ή Example: Your laptop and smart TV connected to the same Wi-Fi.

  • MAN (Metropolitan Area Network) πŸ™οΈ
    A network across a city or large campus.
    πŸ”Ή Example: College Wi-Fi that covers all buildings.

  • WAN (Wide Area Network) 🌍
    Big network that connects the world.
    πŸ”Ή Example: The internet β€” connects servers in the US to users in India.

🌐 OSI Model – 7 Layers

Think of it like sending a parcel πŸ“¦ β€” each layer plays a part!

1️⃣ Application – πŸ’¬ "What You Use"
Apps like WhatsApp, Gmail, Chrome
πŸ’‘ You type a message

2️⃣ Presentation – 🧠 "Formatter"
Encrypts, compresses, translates data
πŸ’‘ Turns emojis/text into computer language

3️⃣ Session – πŸ” "Call Handler"
Starts/stops conversations between devices
πŸ’‘ Keeps your Zoom/Gmail session active

4️⃣ Transport – 🚚 "Safe Delivery"
Breaks data into packets, ensures complete delivery
πŸ’‘ Like packing items in boxes

5️⃣ Network – πŸ—ΊοΈ "Router GPS"
Finds the best route for data
πŸ’‘ Parcel takes fastest route via IP

6️⃣ Data Link – 🧩 "Local Delivery"
Moves data between nearby devices using MAC
πŸ’‘ Delivers to the right flat in a building

7️⃣ Physical – ⚑ "Cables & Signals"
Sends actual bits via wires or Wi-Fi
πŸ’‘ The truck or signal carrying your data

TCP/IP model

real-life systems use a simpler one: TCP/IP model β€” just 4 layers:

  • πŸ‘¨β€πŸ’» Application

  • 🚚 Transport

  • πŸ—Ί Network

  • βš™οΈ Link

These models helped me understand how data travels β€” from clicking "send" to reaching someone's browser!

πŸ“‘ Protocol

A protocol is like a set of rules πŸ“ that computers follow to talk to each other smoothly.

πŸ’¬ Just like how we follow grammar rules to speak a language, computers follow protocols to send/receive data!


πŸ‘¨β€πŸ’» Must-Know Protocols for DevOps


πŸ”— 1. HTTP / HTTPS – 🌐
Used for accessing websites
βœ… Example: Opening Google in a browser
πŸ”’ HTTPS = secure version (data is encrypted)

πŸ›‘οΈ 2. SSH (Secure Shell) – πŸ—οΈ
Used to securely log in to remote servers
βœ… Example: Connecting to a Linux server from your laptop
πŸ’¬ Like a secret tunnel to your server

πŸ“¦ 3. FTP – πŸ“
Used to transfer files between systems
βœ… Example: Uploading files to a web server
πŸ“Œ SFTP is the secure version πŸ”

πŸ“¨ 4. SMTP – πŸ“¬
Used for sending & receiving emails
βœ… Example: Gmail or Outlook behind the scenes
πŸ’‘ DevOps may configure these in mail servers

πŸ“‘ 5. DNS (Domain Name System) – 🧭
Translates website names into IP addresses
βœ… Example: "google.com" β†’ 142.250.67.14
πŸ’¬ Like a phonebook for the internet

πŸ”Œ Port

A port is like a door πŸšͺ on a computer/server that allows specific types of data in or out.

πŸ’‘ Each service (like websites, emails, etc.) uses a specific port number to communicate.

🌐 HTTP (Port 80) – Open websites
βœ… Example: Accessing http://example.com

πŸ”’ HTTPS (Port 443) – Secure websites
βœ… Example: Accessing https://google.com

πŸ› οΈ SSH (Port 22) – Secure login to servers
βœ… Example: ssh user@192.168.1.1 (connect to a server remotely)

πŸ“ FTP (Port 21) – File transfer βœ… Example: Uploading files to a web host

πŸ“¬ SMTP (Port 25) – Send emails
βœ… Example: Used by mail servers to send outgoing emails

🧭 DNS (Port 53) – Website name resolution
βœ… Example: Translating openai.com to an IP address

🌐 IP and MAC Address?

🌐 IP Address – Your Device’s Internet Address

πŸ”’ A unique number that identifies your device on the internet.
πŸ“Œ Used to send/receive data online
βœ… Example: 192.168.1.5
πŸ’‘ Like your home address 🏠 on the internet


πŸ’» MAC Address – Your Device’s Hardware ID

πŸ”‘ A unique code built into your device’s network card.
πŸ“Œ Used within local networks like Wi-Fi
βœ… Example: 00:1A:2B:3C:4D:5E
πŸ’‘ Like your device’s fingerprint 🧀 β€” it never changes

πŸ“¦ Subnetting – Network Divider

πŸ”Ή Breaks a large network into smaller parts (called subnets)
πŸ”Ή Helps organize, secure, and manage IP addresses better
πŸ”Ή Saves IPs and improves performance

βœ… Example: A company splits its network into subnets for HR, Sales, and IT

πŸ’‘ Like dividing a big apartment into smaller flats 🏒➑️🏠


🌐 DNS (Domain Name System) – Internet Phonebook

πŸ”Ή Converts website names into IP addresses
πŸ”Ή Makes browsing easy β€” no need to remember numbers

βœ… Example: google.com ➑️ 142.250.195.174

πŸ’‘ Like finding someone’s number in a phonebook ☎️


πŸ“₯ DHCP (Dynamic Host Configuration Protocol) – IP Giver

πŸ”Ή Automatically gives IP addresses to devices in a network
πŸ”Ή No need to assign IPs manually

βœ… Example: When your phone joins Wi-Fi, it gets an IP from the router

πŸ’‘ Like a receptionist πŸ§‘β€πŸ’Ό giving you a room number in a hotel

πŸ“‘ Router & πŸ”ŒSwitches

πŸ“‘ Router – The Internet Connector

πŸ” Connects different networks (like your home to the internet)
πŸ“Œ Sends data between your devices and the internet
βœ… Example: Your Wi-Fi router at home
πŸ’‘ Like a traffic cop 🚦 directing internet to the right place


πŸ”Œ Switch – The Device Connector

πŸ”— Connects devices inside the same network (like PCs, printers)
πŸ“Œ Sends data within your home or office
βœ… Example: Office switch connecting multiple computers
πŸ’‘ Like a power strip πŸ”Œ for internet β€” connecting many devices locally

🌐 VPC (Virtual Private Cloud)

πŸ”Ή Your own private network inside AWS
πŸ”Ή You control IPs, subnets, gateways, etc.

βœ… Like your own private office space in the cloud 🏒


βš–οΈ Load Balancer

πŸ”Ή Distributes traffic to multiple servers
πŸ”Ή Helps with high availability and better performance

βœ… Like a traffic cop 🚦 sending cars (users) to the least busy road (server)


πŸ”₯ Firewall

πŸ”Ή Blocks or allows network traffic based on rules
πŸ”Ή Protects your network from unwanted access

βœ… Like a security gate 🚧 checking who can enter


πŸ›‘οΈ Security Groups

πŸ”Ή Virtual firewalls for EC2 instances
πŸ”Ή Control which ports (SSH, HTTP, etc.) are open
πŸ”Ή Allow inbound/outbound traffic

βœ… Like door rules πŸšͺ: who can come in, and who can go out

πŸš€ Steps to create EC2 Instance

1️⃣ Login to AWS
πŸ” Go to aws.amazon.com and sign in to your AWS account.

2️⃣ Go to EC2 Dashboard
πŸ–₯️ Search β€œEC2” in the AWS console and open the EC2 service.

3️⃣ Launch Instance
πŸš€ Click β€œLaunch Instance”

4️⃣ Choose AMI (Amazon Machine Image)
🧊 Select an OS like Amazon Linux, Ubuntu, etc.

5️⃣ Choose Instance Type
πŸ“¦ Pick t2.micro (free tier) if you're testing.

6️⃣ Configure Key Pair
πŸ”‘ Create/download a key pair to access your instance later (used for SSH login).

7️⃣ Set Up Security Group
πŸ›‘οΈ Add rules to allow access:

8️⃣ Launch Instance
βœ… Click β€œLaunch” and wait for the instance to run!

9️⃣ Connect to Your Instance
πŸ”— Use SSH with your key file:

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SARVESH VILAS CHAUDHARI
SARVESH VILAS CHAUDHARI