How web browsers request pages in Intro to Computing - Practice Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

What happens first when you type a website address?

When you type a website address (URL) into a browser and press Enter, what is the very first step the browser takes to get the page?

A The browser sends a request to the server asking for the page.

B The browser downloads all images on the page.

C The browser looks up the IP address of the website using DNS.

D The browser renders the page on the screen.

💡 Hint

Think about how the browser finds the website's location on the internet.

Before the browser can ask the server for the page, it needs to find the server's IP address. This is done by asking a DNS server to translate the website name into an IP address.

❓ trace

intermediate

Trace the steps of a browser requesting a page

Put these steps in the correct order for how a browser requests a web page after you type a URL:

A 1,2,3,4

B 1,3,2,4

C 2,3,1,4

D 2,1,3,4

💡 Hint

Remember the browser must find the IP address before sending a request.

The browser first looks up the IP address (DNS lookup), then sends the HTTP request, receives the data, and finally renders the page.

❓ identification

advanced

Identify the protocol used when a browser requests a page

Which protocol does a web browser use to request a web page from a server?

A HTTP

B SSH

C FTP

D SMTP

💡 Hint

This protocol is designed for transferring web pages.

HTTP (HyperText Transfer Protocol) is the standard protocol used by browsers to request and receive web pages.

❓ Comparison

advanced

Compare HTTP and HTTPS in browser requests

What is the main difference between HTTP and HTTPS when a browser requests a page?

A HTTPS encrypts data between browser and server; HTTP does not.

B HTTP is faster than HTTPS because it uses compression.

C HTTPS uses a different port number but sends data unencrypted.

D HTTP requires a password; HTTPS does not.

💡 Hint

Think about security and privacy when browsing.

HTTPS adds encryption to protect data sent between the browser and server, making it secure. HTTP sends data in plain text.

🚀 Application

expert

What happens if DNS lookup fails?

If a browser cannot find the IP address for a website during DNS lookup, what will happen next?

A The browser will try to load the page from its cache anyway.

B The browser will show an error message saying the site cannot be reached.

C The browser will send the request to a random IP address.

D The browser will automatically switch to HTTPS.

💡 Hint

Consider what happens when the browser cannot find where to send the request.

If DNS lookup fails, the browser does not know the server's IP address and cannot send the request, so it shows an error.

Practice

1. What does a web browser send to a server when you type a website address and press Enter?

easy

A. A file containing the webpage

B. A command to shut down the server

C. A request asking for the webpage

D. A message to update the browser

Solution

1. Step 1: Understand browser-server interaction

   When you enter a website address, the browser needs to get the page from the server.

2. Step 2: Identify what the browser sends

   The browser sends a request to the server asking for the webpage data.

3. Final Answer:

   A request asking for the webpage -> Option C

4. Quick Check:

   Browser sends request [OK]

Hint: Browser always sends a request to get pages [OK]

Common Mistakes:

• Thinking browser sends the whole page first
• Confusing request with response
• Assuming browser sends commands to server

2. Which protocol do web browsers use to request pages from servers?

easy

A. HTTP or HTTPS

B. FTP

C. SMTP

D. POP3

Solution

1. Step 1: Recall common internet protocols

   FTP is for file transfer, SMTP and POP3 are for email.

2. Step 2: Identify protocols for web pages

   HTTP and HTTPS are designed for web page requests and responses.

3. Final Answer:

   HTTP or HTTPS -> Option A

4. Quick Check:

   Web pages use HTTP/HTTPS [OK]

Hint: Web pages use HTTP or HTTPS protocols [OK]

Common Mistakes:

• Confusing FTP with HTTP
• Mixing email protocols with web protocols
• Not recognizing HTTPS as secure HTTP

3. Look at this simplified flowchart of a browser requesting a page: 1. Browser sends request to server 2. Server checks if page exists 3. Server sends page if found, else sends error If the server does not find the page, what will the browser receive?

medium

A. An error message like 404 Not Found

B. A blank page with no message

C. The requested webpage content

D. A request to try again

Solution

1. Step 1: Follow the flowchart steps

   The server checks if the page exists after receiving the request.

2. Step 2: Understand server response if page missing

   If the page is missing, the server sends an error message like 404 Not Found.

3. Final Answer:

   An error message like 404 Not Found -> Option A

4. Quick Check:

   Missing page = error 404 message [OK]

Hint: Missing pages return 404 error messages [OK]

Common Mistakes:

• Assuming server sends blank page
• Thinking server asks browser to retry
• Confusing error with page content

4. A browser sends a request to a server but the page never loads. Which of these could be the problem?

medium

A. The user typed the address in uppercase letters

B. The browser sent the wrong page address

C. The browser is using HTTP instead of HTTPS

D. The server is offline or unreachable

Solution

1. Step 1: Analyze possible causes for no page load

   If the server is offline or unreachable, the browser cannot get any response.

2. Step 2: Evaluate other options

   Wrong address usually returns error, HTTP vs HTTPS usually still connects, uppercase letters do not prevent loading.

3. Final Answer:

   The server is offline or unreachable -> Option D

4. Quick Check:

   No response = server offline/unreachable [OK]

Hint: No page load often means server unreachable [OK]

Common Mistakes:

• Thinking uppercase letters break address
• Confusing HTTP and HTTPS connection issues
• Assuming wrong address causes no load instead of error

5. You want to explain how a browser requests a webpage and gets a response using a simple diagram. Which sequence correctly shows the steps?

hard

A. Server sends response -> Browser sends request -> Server processes response -> Browser displays page

B. Browser sends request -> Server processes request -> Server sends response -> Browser displays page

C. Browser sends response -> Server sends request -> Browser processes response -> Server displays page

D. Server sends request -> Browser processes request -> Browser sends response -> Server displays page

Solution

1. Step 1: Understand the communication flow

   The browser initiates by sending a request to the server.

2. Step 2: Follow the correct order of actions

   The server processes the request, sends back a response, and then the browser displays the page.

3. Final Answer:

   Browser sends request -> Server processes request -> Server sends response -> Browser displays page -> Option B

4. Quick Check:

   Request -> Process -> Response -> Display [OK]

Hint: Request starts at browser, response ends at browser [OK]

Common Mistakes:

• Reversing who sends request or response
• Mixing up processing and displaying steps
• Thinking server displays page