SE Web Communications

You are working in a small company, and users are complaining that they cannot access any websites.
You suspect that the issue might be related to the network layer in the TCP/IP model.
What would be the first step to diagnose the problem?

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Answer explanation

The first step to diagnose the problem is to check the network connectivity. Use the 'ping' command to test if the users can reach the gateway or other devices on the network, which helps identify if the issue is at the network layer.

When you open Spotify, what layer is the application running on?

• Transport

• Network

• Application

• Link

Answer explanation

Apps run on the application layer!

Describe the primary function of the network layer in the OSI model

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Answer explanation

The primary function of the network layer in the OSI model is to route packets between devices across different networks, ensuring data is sent from the source to the destination using logical addressing (IP addresses).

You are developing a messaging app that requires reliable data transmission, ensuring that messages arrive at their destination in the correct order, even if it takes slightly longer.
Which protocol should you choose, and why?

• TCP, because it provides reliable, ordered, and error-checked delivery of data packets.

• UDP, because it offers faster data transmission, even though it might result in missing or out-of-order packets.

• UDP, because it automatically resends lost packets without causing any delay.

• TCP, because it is designed to send data only when the network is idle to avoid congestion.

Answer explanation

TCP is the correct choice because it ensures reliable, ordered, and error-checked delivery of messages, which is essential for a messaging app that requires messages to arrive in the correct order.

You are streaming a live video on your computer, but the video keeps buffering intermittently.
You suspect that some data packets might be lost during transmission.
What is the best course of action to improve the video streaming experience?

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Answer explanation

To improve video streaming, consider using a wired connection instead of Wi-Fi, reducing network congestion, or lowering the video quality. These steps can help minimize packet loss and buffering.

A user is trying to connect to a website using HTTPS but is encountering a "Certificate Not Trusted" error. What is the most likely cause of this error?

• The website is using an HTTP URL.

• The SSL certificate is expired or issued by an untrusted Certificate Authority (CA).

• The website's domain is incorrectly configured.

• The DNS server is unreachable.

Answer explanation

The "Certificate Not Trusted" error typically occurs when the SSL certificate is expired or issued by an untrusted Certificate Authority (CA). This indicates a problem with the certificate rather than the URL being HTTP.

Your company’s web server is experiencing delays when receiving data from remote users.
The connection is established, but data transmission is slow.
What layer of the TCP/IP model should you focus on to troubleshoot this performance issue?

• Network Layer

• Transport Layer

• Application Layer

• Physical Layer

Answer explanation

The Transport Layer is responsible for end-to-end communication and data flow control. Since the connection is established but data transmission is slow, focusing on this layer can help identify issues affecting performance.

Your company’s website is accessible through both HTTP and HTTPS, but some users are still using the HTTP version. Why is implementing a server-side redirect from HTTP to HTTPS the best way to ensure all users access the site securely via HTTPS?

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Answer explanation

Implementing a server-side redirect from HTTP to HTTPS ensures that all users are automatically directed to the secure version of the site, enhancing security and preventing data interception, which is crucial for user trust.

A user reports that they are unable to access a secure website and receive a "Connection Timed Out" error.
What is the most likely cause of this issue?

• The SSL certificate is invalid.

• The server is down or unreachable.

• The user's browser is outdated.

• The website's domain is not registered.

Answer explanation

The "Connection Timed Out" error typically indicates that the server is not responding, which suggests that the server is down or unreachable. Other options like SSL issues or browser problems would not directly cause a timeout.

You are setting up a secure e-commerce website and want to protect user data during transmission.

Identify which protocol should be used between the server and the browser.

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Answer explanation

To protect user data during transmission on an e-commerce website, you should use HTTPS (HTTP Secure). It encrypts the data exchanged between the server and the browser, ensuring confidentiality and integrity.