Computer Science Basics for Beginners

🔍 What Happens When You Type a URL?

When you type a web address (URL) like https://udaanpath.com and hit enter, a lot of things happen behind the scenes to bring that website to your screen. Let’s break down this fascinating journey step by step.

🌐 Step-by-Step Breakdown

1. URL is entered: You type https://udaanpath.com in the browser and press Enter.
2. Browser checks cache: Your browser checks if it has a recent copy of the page in its cache.
3. DNS Resolution: The browser contacts a DNS (Domain Name System) server to find the IP address of udaanpath.com. For example, it might return something like 104.21.32.140.
4. Browser makes an HTTPS request: It creates a request to this IP address asking for the homepage.
5. Server processes request: The UdaanPath server receives your request, processes it, and decides what content to send back.
6. Response is sent back: The server sends an HTTP response containing HTML, CSS, JavaScript, and other data.
7. Browser renders page: The browser receives the content and builds the page you see — complete with layout, colors, text, and interactivity.

📌 Key Components Involved

• Browser: The software (like Chrome, Firefox) that renders the web page.
• DNS Server: Like a phonebook for the internet. Maps domain names to IP addresses.
• Web Server: Hosts website files and responds to HTTP requests.
• TCP/IP: Protocols that ensure data is sent and received accurately over the network.
• HTTP/HTTPS: Protocols for transferring web content securely (HTTPS uses SSL encryption).

🌐 Domain vs IP Address

Domains are human-readable (like udaanpath.com), but machines talk in IP addresses (like 104.21.32.140).

📦 DNS Cache Hierarchy

• Browser Cache
• Operating System Cache
• Router DNS Cache
• ISP DNS Cache
• Root DNS Servers (if all else fails)

🚀 HTTPS Request Example

GET / HTTP/1.1
Host: udaanpath.com
User-Agent: Chrome/115.0
Accept: text/html
  

💡 Interesting Fact

A modern web page may require dozens or hundreds of additional requests for images, scripts, fonts, stylesheets, and more — all fetched after the first HTML file is received.

📝 Practice Questions

1. What is DNS and what is its purpose?
2. Explain what happens when you visit https://udaanpath.com.
3. What’s the difference between HTTP and HTTPS?
4. What are the roles of IP address and DNS server in this process?

✅ Coming Next

In the next chapter, we’ll explore APIs & Databases (Overview) — understanding how apps talk to servers and where all the data is stored.