HTTP and HTTPS in HLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding HTTP Request Methods

Which HTTP method is designed specifically to retrieve data from a server without causing any side effects?

A PUT

B POST

C GET

D DELETE

💡 Hint

Think about the method that only asks for information without changing anything.

The GET method is used to request data from a server and should not change any data on the server. POST, PUT, and DELETE are used to modify data.

❓ Architecture

intermediate

Choosing Between HTTP and HTTPS for a Web Application

You are designing a web application that handles user login and sensitive data. Which protocol should you choose to ensure data security during transmission?

A HTTPS because it encrypts data between client and server

B HTTP because it uses fewer resources on the server

C HTTP because it is faster and simpler

D Either HTTP or HTTPS since both transmit data the same way

💡 Hint

Consider which protocol protects data from being read by others during transmission.

HTTPS uses encryption (TLS/SSL) to secure data between client and server, protecting sensitive information like passwords. HTTP transmits data in plain text, which is insecure.

❓ scaling

advanced

Scaling HTTPS Traffic for a High-Traffic Website

Your website uses HTTPS and experiences a sudden increase in traffic. Which approach best helps maintain performance while keeping secure connections?

A Use HTTP only on backend servers and HTTPS only on clients

B Terminate SSL/TLS at a load balancer and forward unencrypted traffic to backend servers

C Disable HTTPS to reduce encryption overhead during high traffic

D Use HTTP/2 without TLS to improve speed

💡 Hint

Think about offloading encryption work to a dedicated component to reduce load on backend servers.

Terminating SSL/TLS at the load balancer allows it to handle encryption/decryption, reducing CPU load on backend servers. Forwarding unencrypted traffic internally is safe within a trusted network.

❓ tradeoff

advanced

Tradeoffs Between HTTP and HTTPS for Static Content Delivery

For delivering static images and videos on a public website, what is a key tradeoff when choosing HTTPS over HTTP?

A HTTPS increases security but may add slight latency due to encryption

B HTTP is more secure because it uses less CPU

C HTTPS reduces bandwidth usage compared to HTTP

D HTTP supports caching while HTTPS does not

💡 Hint

Consider the impact of encryption on speed and security.

HTTPS encrypts data, adding some latency and CPU overhead, but it protects data integrity and privacy. HTTP is faster but insecure. Both support caching.

❓ estimation

expert

Estimating TLS Handshake Overhead in HTTPS Connections

When a client establishes an HTTPS connection, the TLS handshake adds extra time before data transfer begins. Approximately how many round-trip times (RTTs) does a full TLS 1.3 handshake require before encrypted data can be sent?

A Zero RTTs

B Two RTTs

C Three RTTs

D One RTT

💡 Hint

TLS 1.3 improved handshake speed compared to previous versions.

TLS 1.3 requires one round-trip time (RTT) for a full handshake before encrypted data can be sent. It also supports zero-RTT for resumed sessions, but the question asks about a full handshake.

Practice

1. What is the main difference between HTTP and HTTPS?

easy

A. HTTPS encrypts data while HTTP does not

B. HTTP encrypts data while HTTPS does not

C. HTTP is faster because it uses encryption

D. HTTPS does not use any encryption

Solution

1. Step 1: Understand HTTP basics

   HTTP transfers data without encryption, so data can be seen by others.

2. Step 2: Understand HTTPS encryption

   HTTPS adds encryption to protect data from being read by others during transfer.

3. Final Answer:

   HTTPS encrypts data while HTTP does not -> Option A

4. Quick Check:

   Encryption = HTTPS [OK]

Hint: HTTPS always means encrypted data transfer [OK]

Common Mistakes:

• Thinking HTTP encrypts data
• Believing HTTPS is slower because of encryption
• Confusing HTTP and HTTPS roles

2. Which URL prefix indicates a secure connection using HTTPS?

easy

A. http://

B. https://

C. ftp://

D. file://

Solution

1. Step 1: Identify URL prefixes

   URLs starting with http:// use HTTP, which is not secure.

2. Step 2: Recognize HTTPS prefix

   URLs starting with https:// use HTTPS, which is secure and encrypted.

3. Final Answer:

   https:// -> Option B

4. Quick Check:

   Secure URL prefix = https:// [OK]

Hint: Secure URLs start with https:// [OK]

Common Mistakes:

• Choosing http:// as secure
• Confusing ftp:// with HTTPS
• Not recognizing URL prefixes

3. Consider this simplified request flow for a website:

1. Client sends HTTP request
2. Server responds with redirect to HTTPS URL
3. Client sends HTTPS request
4. Server sends secure response

What is the main purpose of step 2 in this flow?

medium

A. To encrypt data before sending it

B. To send the website content unencrypted

C. To close the connection immediately

D. To tell the client to use a secure connection

Solution

1. Step 1: Analyze step 2 action

   Server sends a redirect response telling client to change URL to HTTPS.

2. Step 2: Understand redirect purpose

   This redirect forces client to use a secure encrypted connection for next request.

3. Final Answer:

   To tell the client to use a secure connection -> Option D

4. Quick Check:

   Redirect to HTTPS = secure connection [OK]

Hint: Redirects to HTTPS enforce secure connections [OK]

Common Mistakes:

• Thinking redirect encrypts data itself
• Believing redirect closes connection
• Confusing redirect with content delivery

4. A developer wrote this code snippet to check if a URL uses HTTPS:

if url.startswith('http://'):
    print('Secure connection')
else:
    print('Not secure')

What is the error in this code?

medium

A. It should check for 'https://' to confirm security

B. The print statements are reversed

C. The method 'startswith' does not exist

D. It should use 'http://' to confirm security

Solution

1. Step 1: Understand the check logic

   The code checks if URL starts with 'http://', then says 'Secure connection'.

2. Step 2: Identify correct prefix for security

   Only URLs starting with 'https://' are secure, so the check is wrong.

3. Final Answer:

   It should check for 'https://' to confirm security -> Option A

4. Quick Check:

   Check 'https://' for security [OK]

Hint: Check for 'https://' prefix to confirm security [OK]

Common Mistakes:

• Confusing 'http://' as secure
• Reversing print messages
• Using non-existent string methods

5. You are designing a web service that must protect user data and build trust. Which approach best ensures secure communication and user confidence?

hard

A. Use HTTP and encrypt data manually in the application layer

B. Use HTTP for faster data transfer and add a login page

C. Use HTTPS with a valid SSL certificate and redirect all HTTP requests to HTTPS

D. Use HTTPS only on the login page and HTTP elsewhere

Solution

1. Step 1: Identify security needs

   Protecting user data requires encryption for all communication, not just parts.

2. Step 2: Evaluate options for secure design

   Using HTTPS with a valid SSL certificate and redirecting HTTP to HTTPS ensures all data is encrypted and users see trust indicators.

3. Final Answer:

   Use HTTPS with a valid SSL certificate and redirect all HTTP requests to HTTPS -> Option C

4. Quick Check:

   Full HTTPS with redirect = best security [OK]

Hint: Always redirect HTTP to HTTPS with valid SSL for trust [OK]

Common Mistakes:

• Using HTTP for speed over security
• Encrypting only parts of communication
• Mixing HTTP and HTTPS causing confusion