Unit 6 Session 3: HTTP, Email, FTP, WWW, Search, and TELNET | IT 231 BBA Slides

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Unit 6 · Session 3

HTTP, Email, FTP, WWW, Search, and TELNET

IT 231: IT and Applications (BBA)

Today's focus

  1. Key Internet Protocols: HTTP, Email, and FTP
  2. The World Wide Web and Search Engines
  3. Remote Login (TELNET)

Key Internet Protocols: HTTP, Email, and FTP

Learning Objectives 🎯

By the end of this session, you will be able to:

  • ✅ Define HTTP and its role in the World Wide Web.
  • ✅ Identify the key protocols used for sending and receiving email.
  • ✅ Define FTP and its purpose for file transfers.

Beyond TCP/IP: Application Protocols

While TCP/IP provides the internet's foundation, specialized Application Layer protocols handle the services we use daily.

Think of TCP/IP as the postal service, and these protocols as the different types of mail you can send:

  • 💌 Letters (Email)
  • 📦 Packages (FTP)
  • 📰 Magazines (HTTP)

1. HTTP: The Language of the Web 🌐

HTTP (Hypertext Transfer Protocol) is the protocol that powers the World Wide Web. It defines how browsers and servers communicate.

The process is a simple request-response cycle:

  1. You type a URL in your browser.
  2. Your browser sends an HTTP Request to the web server.
  3. The server sends back an HTTP Response containing the webpage content.

Security Matters: HTTP vs. HTTPS 🔒

HTTP

  • Standard HTTP
  • Unencrypted
  • Data sent in plain text
  • Vulnerable to interception

HTTPS

  • HTTP Secure
  • Encrypted communication
  • Protects data with SSL/TLS
  • Essential for sensitive info

Key Point: Always look for the lock icon! HTTPS protects your passwords, credit card numbers, and personal data.

Practical Application in Nepal 🇳🇵

Using Online Services Securely

When you log into a Nepali service like eSewa, Khalti, or your bank's online portal, your browser uses HTTPS.

This encryption is crucial for protecting your financial details and login credentials from being stolen over public Wi-Fi or other insecure networks.

2. How Email Travels: A Team of Protocols 📧

Sending and receiving email isn't handled by a single protocol. It requires a coordinated effort between multiple protocols.

We'll look at the three main players:

  • SMTP: For sending mail.
  • POP3: For receiving mail (the old way).
  • IMAP: For receiving mail (the modern way).

The Email Protocols 📊

SMTP

Simple Mail Transfer Protocol

The standard for SENDING email from a client to a server.

POP3

Post Office Protocol 3

Used for RECEIVING. Downloads email to a single device and often deletes it from the server.

IMAP

Internet Message Access Protocol

Also for RECEIVING. Syncs with the server, allowing access from multiple devices.

POP3 vs. IMAP: Which is for you?

Scenario:

You use a laptop at work, a personal smartphone, and a tablet at home to check your university email. You want to see the same inbox, sent items, and folders on all devices.

Which protocol is better for this situation?

Answer: IMAP! It synchronizes all your actions across all devices by keeping the master copy of your email on the server.

3. FTP: The Heavy Lifter for Files 📂

FTP (File Transfer Protocol) is a specialized protocol designed to transfer computer files from one host to another over the internet.

Common uses include:

  • Uploading website files to a hosting server.
  • Downloading large software packages or data sets.
  • Sharing files that are too large for email attachments.

Summary & Key Takeaways ⚡

  • HTTP is the foundation of the World Wide Web, enabling communication between your browser and web servers. HTTPS adds a critical layer of security.
  • Email relies on a combination of protocols: SMTP is exclusively for sending, while POP3 or IMAP are used for receiving.
  • IMAP is the modern standard for email access across multiple devices, as it syncs with the server.
  • FTP is the go-to protocol for transferring files between computers, especially for web development and large file distribution.

The World Wide Web and Search Engines

Next focus

In this part of today's lecture, you will be able to:

  • ✅ Differentiate between the Internet and the World Wide Web.
  • ✅ Describe the roles of a web browser and a web server.
  • ✅ Explain the basic function of a search engine.

Internet vs. World Wide Web

They are not the same thing! It's a common misconception.

The Internet 🌐

  • The global network of computers.
  • The physical infrastructure (cables, routers, servers).
  • Analogy: The road network of a country.

The World Wide Web (WWW) 🕸️

  • A service that runs on the Internet.
  • A system of interlinked documents.
  • Analogy: The houses, shops, and destinations along the roads.

⚡ Key Idea: The Web uses the Internet to exist, but the Internet is more than just the Web (it also supports email, FTP, etc.).

Key Components of the Web

How do we access information on the Web? Through a client-server model.

Web Browser (Client)

Software on your device used to view websites.

  • Requests web pages.
  • Renders HTML, CSS, and JavaScript.
  • Examples: Chrome, Firefox, Safari.

Web Server (Server)

Software on a remote computer that stores websites.

  • Listens for requests from browsers.
  • Serves web pages upon request.
  • Examples: Apache, Nginx.

The Web Address: URL

Every resource on the Web has a unique address called a Uniform Resource Locator (URL).

Anatomy of a URL

https://www.tu.edu.np/results

  • https:// - The protocol (HyperText Transfer Protocol Secure).
  • www.tu.edu.np - The domain name (Tribhuvan University, Nepal).
  • /results - The path to a specific resource on that server.

The Problem: Information Overload

The Web contains billions of pages. How can we find anything?

🔍 Enter Search Engines

Definition: A search engine is a software system designed to search for information on the World Wide Web.

How Search Engines Work: A 3-Step Process

1. Crawling 🕷️

Automated "spiders" follow links to discover pages.

2. Indexing 📚

Content is analyzed and stored in a huge database (the index).

3. Ranking 📊

An algorithm sorts results by relevance and authority.

Step 1: Crawling

Crawling: The process of systematically browsing the web to discover new and updated content.

  • Automated programs called "spiders" or "crawlers" perform this task.
  • They start with a list of known URLs and follow hyperlinks on those pages to find new ones.
  • This process is continuous to keep up with the ever-changing web.

Step 2: Indexing

Indexing: The process of storing and organizing the content found during crawling.

  • Once a page is crawled, the search engine analyzes its content (text, images, keywords).
  • This information is stored in a massive database, like a giant library index for the entire web.
  • The index allows for nearly instantaneous retrieval of relevant pages.

The purpose of the index is speed. Searching the entire web in real-time is impossible!

Step 3: Ranking

Ranking: The process of deciding the order in which to display results for a user's query.

  • When you search, the engine queries its index, not the live web.
  • A complex algorithm evaluates hundreds of factors to determine relevance.
  • Factors include keywords, page authority, user location, and freshness of content.
  • Examples: Google Search, Bing, DuckDuckGo.

Practical Application in Nepal

Search engines adapt results based on your context, like location.

Try This Search

Search for "restaurants near me" on your phone.

  • The search engine uses your location in Nepal (e.g., Pokhara, Kathmandu) to provide local results.
  • Now search for "latest news". You'll likely see results from Nepali news portals like The Kathmandu Post or Onlinekhabar ranked highly.
  • This is the ranking algorithm at work, prioritizing local relevance.

Key Takeaways ⚡

  • The Web is a service that runs on the Internet. They are two different things.
  • A web browser (client) requests pages from a web server.
  • Search engines find information through a three-step process: crawling, indexing, and ranking.
  • The index is a critical database that makes fast searching possible.

Remote Login (TELNET)

What is TELNET?

TELNET (Teletype Network) is an early network protocol used to provide a bidirectional interactive text-oriented communication facility.

  • Allows users to connect to a remote computer.
  • Acts as a "dumb terminal" passing keystrokes directly to the server.
  • Commonly used for remote administration of servers and routers.

How It Works

  1. Client Request: Connection is established via an IP and port (usually port 23).
  2. Authentication: Username and password are requested.
  3. Execution: Commands are executed remotely.
  4. Output: Text output is returned to the user's screen.

The Security Vulnerability ⚠️

TELNET transmits all data in plain text, including usernames and passwords!

  • Susceptible to network sniffing.
  • Largely replaced by SSH (Secure Shell) which encrypts all traffic.
  • Rarely used today on public networks.

Thank You

Questions before we wrap this hour?

Next: Unit 6 · Session 4 — Web Pages, E-Commerce, Smart City, Intranet and Extranet

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