Git is a distributed version control system. It is designed to efficiently manage and track changes in source code during the software development process.

Why git is used?

Git is used to solve multiple problems of software development lifecycle

• Track & Manage changes in source code

• Collaboration between developers/stakeholders

• Branching & Merging of source code.

• Distributed Architecture

Git Basics & Core Terminologies

Git is widely used Version Control System which help tracking the code changes. It acts like a “time machine” for source code.

The following are the core terminologies for Git

• Repo/Repository - a repository is the main project folder that Git tracks. It contains all project files and the complete version history.

• Working Directory - The local directory on your computer where you will changes the code

• Staging Area - It is a waiting area where you will put the modified files before comming it.

• Commit - The commit is a snapshot or save point of a project. Each commit has a unique ID, an author, a timestamp and a message explaining the changes made.

• Branch - An independent line of development. Branching allows developers to work on new features or bug fixes without affecting the main codebase, keeping the main branch stable.

• Head - A pointer that indicates your current position in the project's history.

• Merge - The process of integrating changes from one branch to other branch.

• Remote - It is a secondary copy of the project/repository which is hosted on an external server.

Common Git commands

Here is the list of common git commands:

1. git init: Initializes Git tracking in a local project folder, making it a repository.

2. git status: Shows the current state of the working directory and staging area (which files are modified, staged, or untracked).

3. git add <file> / git add .: Stage specific file changes or all changes in the current directory for the next commit.

4. git commit -m "message": Records the staged changes as a permanent snapshot in the repository with a descriptive message.

5. git log: Displays the history of commits for the current branch.

6. git push: Uploads your local commits to a remote repository.

7. git pull: Fetches changes from a remote repository and merges them into your current local branch.

The commands are listed in the same sequence in which they are used.

Basic Flow of git commands

In this article, we’ll break down modems, routers, switches, hubs, firewalls, and load balancers—what each one does, how they differ, and how they work together in real-world systems.

High-Level View: How the Internet Reaches Your (Home / Office )

At a very high level, the journey looks like this:

Internet → Modem → Router → Switch → Your Devices (Laptop, Mobile, Servers)

In production systems, this chain expands further to include firewalls and load balancers, but the core idea remains the same.

Let’s now understand each component—one responsibility at a time.

What is a Modem, and how does it connect your network to the internet?

Primary Responsibility

👉 Convert signals from Internet Service Provider (ISP) into usable internet data.

What a Modem Actually Does

• ISPs send data over cable, fiber, DSL, or telephone lines

• These signals are not Ethernet

• A modem modulates and demodulates signals (that’s where the name comes from)

Analogy

Think of a modem as:

A language translator between your ISP and your network.

Without a modem:

• Your devices cannot talk directly to the ISP

• There is no internet, only a physical cable

📌 Important:

A modem does not manage traffic, devices, or security—it just establishes the connection.

What is a Router and how it directs traffic?

Primary responsibility:

👉 Decide where data should go.

What a Router Does

• Connects multiple networks (LAN ↔ Internet)

• Assigns private IP addresses to devices

• Performs NAT (Network Address Translation)

• Routes packets to the correct destination

Analogy

A router is like:

A traffic police officer at a major junction.

It looks at:

• Destination IP

• Routing rules

• Network boundaries

…and forwards packets accordingly.

Switch vs Hub: how local networks actually work?

Both hubs and switches connect devices within the same network, but they behave very differently.

What Is a Hub?

Primary responsibility:

👉 Broadcast everything to everyone.

• Sends incoming data to all ports

• No intelligence

• Causes collisions

• Almost obsolete today

Analogy:

A person shouting in a crowded room—everyone hears it, even if it’s not for them.

What Is a Switch?

Primary responsibility:

👉 Deliver data only to the intended device.

• Uses MAC address table

• Forwards packets only to the correct port

• Faster, safer, efficient

What is a Firewall and why security lives here?

What is a Load Balancer and why scalable systems need it?

How all these devices work together in a real-world setup?

DNS stands for Domain Name System. In simple words, DNS is the Phone Book of the Internet.

Why are DNS records needed?

The Human remembers names like google.com, github.com, etc. While the computers communicate using IP addresses like 101.102.103.104. DNS translates the human-friendly names into machine-friendly IP Addresses.

What an NS Record is (who is responsible for a domain)

An NS Record (Name Server Record) tells the Internet who is responsible for a domain’s DNS

What an A Record is (domain → IPv4 address)

An A Record (Address Record) maps a domain name to an IPv4 Address. It tells the internet where (which server) your domain lives.

What an AAAA Record is (domain → IPv6 address)

IPv4 addresses are limited. IPv6 was created to solve address exhaustion. It is similar to A Record.

What a CNAME Record is (one name pointing to another name)

A CName Record (Cononical Name Record) makes on domain name point to another domain name.

What an MX Record is (how emails find your mail server)

An MX Record (Mail Exchange Record) tells the Internet which mail servers should receive email for your domain.

What a TXT Record is (extra information and verification)

A TXT Record (Text Record) stores extra information about a domain and is commonly used for verification, security, and configuration.

How all DNS records work together for one website

DNS records work together to answer four questions:

1. Who manages this domain? (NS)

   1. The value of NS tells the Internet, “Who manages this domain?”

2. Where is the website hosted? (A / AAAA / CNAME)

   1. Browsers use these to find the web server

3. Where should emails go? (NX)

   1. The email server uses these values todetermine where to deliver emails

4. Can this domain be trusted? (TXT)

   1. Prevents email spoofing

   2. Verify domain ownership

   3. Enable services & SSL