Computer Network | Data Link Layer Important Questions with Answers for BCA | MCA | BTech

Are you preparing for your BCA, MCA, or BTech exams? Mastering computer networks is crucial for your success. In this article, we have compiled a comprehensive list of important computer network questions with answers tailored for BCA, MCA, and BTech students. These questions will help you understand key concepts, enhance your knowledge, and ace your exams. Dive into our detailed guide and boost your confidence in computer networks.

Computer Network Important Questions with Answers for BCA | MCA | BTech

Computer Network Important Questions with Answers 

1. Describe Briefly on Network Edge

The network edge is like the outer border of a network. It's where devices like computers, smartphones, and tablets connect to the internet. Imagine a neighborhood where each house (device) connects to the main road (internet). These connections happen through routers and switches, which are like the gateways between your home and the main road. The network edge is important because it handles the traffic between your devices and the larger network, making sure data gets where it needs to go efficiently.

2. Explain the OSI Reference Model

The OSI (Open Systems Interconnection) model is a framework used to understand how different network protocols interact and communicate. Think of it as a recipe with seven steps to ensure successful data exchange between devices:

1. Physical Layer: This is like the wiring and cables that connect your devices. It deals with the physical connection between devices.
2. Data Link Layer: Think of this as traffic lights on the road. It controls data transfer between neighboring devices and ensures error-free transmission.
3. Network Layer: This is like the GPS in your car. It determines the best route for data to travel across networks.
4. Transport Layer: Imagine sending a package. This layer ensures the package (data) arrives safely and in the correct order.
5. Session Layer: Like a phone call, this layer establishes, manages, and terminates connections between devices.
6. Presentation Layer: This is like translating languages. It converts data into a readable format for the application layer.
7. Application Layer: This is where you interact directly, like sending an email or browsing the web. It includes protocols like HTTP and FTP.

3. List and Explain Four Layers of the TCP/IP Model with a Suitable Diagram

The TCP/IP model is a simplified version of the OSI model with four layers. It helps explain how data travels from one device to another over the internet. Here's a breakdown:

1. Link Layer:

• Example: Imagine the cables and Wi-Fi signals that connect your devices to the internet.
• Function: It handles the physical connection and data transfer between devices on the same network.

2. Internet Layer:

• Example: Think of this as a GPS that finds the best route for your data.
• Function: It routes data from the source device to the destination device, even if they are on different networks. It uses IP addresses to do this.

3. Transport Layer:

• Example: Similar to a mail delivery service that ensures your letter reaches the recipient.
• Function: It provides reliable data transfer between devices. It ensures that data is delivered in the correct order and without errors. Protocols like TCP and UDP operate at this layer.

4. Application Layer:

• Example: This is like the software applications you use, such as web browsers and email clients.
• Function: It includes protocols that support various network applications. This layer interacts directly with the end-user. Examples include HTTP for web browsing, FTP for file transfer, and SMTP for email.

Diagram

In simple terms, the TCP/IP model helps your device communicate with others by passing data through these four layers, ensuring it reaches its destination accurately and efficiently.

4. Describe the history of networking

Networking started as a way for computers to talk to each other. Imagine how friends send letters to share the news. In the 1960s, researchers wanted computers to send messages too. They created the ARPANET, which is like the first ever computer post office. Over time, more computers joined in, making it easier for everyone to share information quickly. By the 1990s, the internet was born, connecting people and computers all around the world. Think of it as a huge party where everyone can chat and share pictures instantly.

2. Differentiate between baseband transmission and passband transmission

Baseband Transmission: Baseband transmission is like speaking directly into a walkie-talkie. You use the entire channel to send your message. For example, when you talk to your friend through a tin can telephone, the whole string is used just for your voice. Similarly, baseband uses the whole bandwidth for one signal at a time, making it simple but limited to short distances.

Passband Transmission: Passband transmission is more like a radio station. It sends multiple signals over the same channel by changing the frequency. Think of different radio stations playing music at different frequencies, and your radio can tune into each one separately. Passband transmission allows more data to travel longer distances by using different frequencies within the same channel.

5. Write short notes on FDM, TDM, and CDM

Frequency Division Multiplexing (FDM): FDM is like sharing a road with multiple lanes. Each car (signal) travels in its own lane (frequency). For example, imagine different TV channels being broadcasted over the air. Each channel has its own frequency, so you can switch between channels without them interfering with each other. This way, multiple signals travel simultaneously without mixing up.

Time Division Multiplexing (TDM): TDM is like a round-robin game where players take turns. Imagine kids sharing a single swing in a park, each getting a fixed amount of time to swing before the next kid takes over. In TDM, each signal gets a time slot to use the entire channel. For instance, during a phone call, your voice data is sent in small time slots, one after another, so multiple calls can share the same line.

Code Division Multiplexing (CDM): CDM is like using secret codes to send messages in a crowded room. Imagine everyone talking at once but using different languages. You can understand the conversation in your language but not the others. In CDM, each signal is given a unique code, allowing multiple signals to share the same channel without interfering. This is how technologies like 3G in mobile phones allow many users to communicate simultaneously.

6. Describe different implementations of Ethernet

Ethernet is a way to connect computers so they can share information. Think of it as a super-fast courier service within an office. Here are a few types:

Ethernet (Standard): This is like a regular office courier that delivers messages to different desks. Computers connect using cables and can send data up to 10 Mbps. It's reliable for small networks.

Fast Ethernet: This is like upgrading to a motorbike courier service. It speeds up data transfer to 100 Mbps. Offices with more employees or higher data need to use this to share information quickly.

Gigabit Ethernet: Imagine switching to a sports car courier. Gigabit Ethernet transfers data at 1000 Mbps (1 Gbps), making it great for large networks like university campuses or big companies where lots of data moves around.

10-Gigabit Ethernet: This is like using a jet plane for deliveries. It provides data transfer speeds of up to 10,000 Mbps (10 Gbps). Large data centers and enterprise networks use this for handling huge amounts of data efficiently.

Each type of Ethernet builds on the previous one, providing faster and more efficient ways to connect and share data as technology advances.

7. List and Explain Different Wireless LANs

1. Wi-Fi (Wireless Fidelity): Wi-Fi is the most common type of wireless LAN. It allows devices like laptops, smartphones, and tablets to connect to the internet or a local network without using cables. Imagine a coffee shop where people are using their devices to browse the web; they're likely using Wi-Fi.

2. Bluetooth: Bluetooth is a short-range wireless LAN that connects devices over a shorter distance than Wi-Fi. It's used for connecting headphones, keyboards, and other peripherals to your computer or phone. Think of it like an invisible cable connecting your wireless earbuds to your phone.

3. Zigbee: Zigbee is used for smart home devices like lights, thermostats, and security systems. It consumes less power and covers a smaller area compared to Wi-Fi. For example, Zigbee is what allows your smart light bulb to communicate with your home automation system.

4. Li-Fi (Light Fidelity): Li-Fi uses light waves instead of radio waves to transmit data. It's similar to Wi-Fi but can be used in places where radio waves can't reach, like underwater or in hospitals. Imagine using your ceiling light to also provide internet to your devices.

8. Describe Multiprotocol Label Switching (MPLS)

Multiprotocol Label Switching (MPLS) is a technique used in high-performance telecommunications networks. It directs data from one network node to the next based on short path labels rather than long network addresses, speeding up the data flow.

Imagine you're on a road trip. Normally, you would follow a map (network address) to get to your destination. With MPLS, you follow a series of signposts (labels) that direct you to your destination faster and more efficiently. This is particularly useful for managing traffic on busy networks and ensuring that data gets to where it needs to go quickly and reliably.

9. Differentiate Between Byte-oriented Protocols and Bit-oriented Protocols

• Byte-oriented Protocols: These protocols use a byte (a group of 8 bits) as the unit of transmission. Think of it like reading a book where each page is made up of words (bytes). An example is the PPP (Point-to-Point Protocol), used for direct connections between two network nodes.
• Bit-oriented Protocols: These protocols use individual bits as the unit of transmission. It's like reading a book letter by letter instead of word by word. An example is the HDLC (High-Level Data Link Control) protocol, which is more efficient than byte-oriented protocols because it can pack more information into each transmission.

10. Write Short Notes on Clock-based Framing

Clock-based framing is a method used in telecommunications to organize data for transmission. It's like a train schedule where each train (data) has a specific time to depart and arrive. This ensures that data arrives in the correct order and at the right time, preventing errors and confusion.

For example, when you're watching a live sports event on TV, clock-based framing ensures that the video and audio stay in sync, giving you a smooth viewing experience.

11. Describe Hamming Codes in Detail

Hamming codes are a method of error detection and correction used in digital communications. They allow the receiver to detect and correct errors that may occur during data transmission.

Imagine you're sending a message with a few typos to a friend. Hamming codes are like a spell checker that not only detects the typos but also suggests the correct words. This ensures that the message your friend receives is accurate.

In technical terms, Hamming codes add extra bits to the data you're sending, which helps the receiver identify and correct any errors. This is crucial in applications where accuracy is important, like in computer memory or during data transmission over a noisy channel.

12. Comparing Binary Convolutional Codes, Reed-Solomon Codes, and Low-Density Parity-Check (LDPC) Codes

1. Binary Convolutional Codes

Explanation:

• Think of this as a security guard who checks every passenger's ticket in a sequence.
• Every bit of data is checked continuously, and errors can be corrected on the fly.
• Suitable for situations where data is streamed, like in live video broadcasts.

Real-life Example:

• Imagine a line of people entering a concert. The guard checks each person's ticket one by one. If someone tries to sneak in with a fake ticket, the guard can catch it immediately.

2. Reed-Solomon Codes

Explanation:

• This is like having a summary check at the end of a large batch of tickets.
• It checks blocks of data and can correct errors in multiple places within that block.
• Often used in CDs, DVDs, and QR codes, where large chunks of data need error correction.

Real-life Example:

• Picture a group of tickets being scanned by a machine all at once at a movie theater. If there are errors in some tickets, the machine can still figure out the correct number of valid tickets.

3. Low-Density Parity-Check (LDPC) Codes

Explanation:

• These codes use a method similar to a jigsaw puzzle. They use many small pieces of data to check for errors.
• Very efficient and used in high-speed data communication like satellite and 5G networks.

Real-life Example:

• Imagine assembling a large jigsaw puzzle. Even if a few pieces are missing, you can still figure out the complete picture because the rest of the pieces help you understand the missing parts.

13. Explain Different Error Detecting Codes: 

Error-detecting codes are techniques used in data communication to ensure data integrity. One common method is the parity check. Imagine sending a package where you include an extra item, like a small colored stone. If the recipient gets an even number of stones, they know the package arrived intact. If odd, they know there's been an error. Similarly, error-detecting codes verify if data has been transmitted correctly by adding redundancy bits that allow receivers to check for errors.

14. What are the services provided to the network layer by the data link layer? Explain.

The data link layer ensures reliable data transfer across physical links. It offers several services to the network layer above it. For instance, it manages data framing, error detection, and flow control. Think of it like a postal service that not only ensures packages are correctly addressed and delivered (framing) but also checks for damages (error detection) and adjusts delivery speeds based on traffic (flow control).

15. Explain the Four Basic Framing Methods:

Framing in networking involves dividing a stream of data into manageable chunks for transmission. Four common methods include:

• Byte Count: Adding a header that specifies the number of bytes in the frame.
• Byte Stuffing: Inserting special characters to mark the beginning and end of each frame.
• Bit-oriented: Using bit patterns to mark the start and end of frames.
• Flag: Adding flags at the beginning and end of each frame.

16. Describe Data Link Layer Error Control and Flow Control

1. Error Control:

Imagine sending a letter by mail. You want to make sure it reaches the recipient without any mistakes. Similarly, in a computer network, error control ensures that data sent from one device to another arrives correctly. If any errors are found, the system corrects them.

For example, think of two friends sending messages through a phone. Friend A sends a message to Friend B. If Friend B receives a message that doesn’t make sense, Friend B asks Friend A to resend it. This is how error control works. It ensures messages are received accurately and, if not, they are resent until they are correct.

2. Flow Control:

Flow control is like a conversation between two friends where one speaks and the other listens without interrupting. If Friend A speaks too fast, Friend B might miss some parts. So, Friend A needs to speak at a pace that Friend B can follow.

In networking, flow control ensures that the sender doesn’t overwhelm the receiver with too much data at once. It helps manage the speed of data transmission, so the receiver can process everything without losing any information.

17. Explain Simplex Protocol

The simplex protocol is like a one-way street. Data travels in only one direction, like a TV broadcast. The TV station sends signals to your TV, but your TV doesn't send signals back.

In computer networks, simplex means data can only flow from the sender to the receiver. There’s no way for the receiver to send any data back to the sender. This is useful in situations where only one-way communication is needed.

18. Differentiate between stop and wait protocols for error-free channels and Noisy channels.

Stop and Wait for Error-Free Channels:

Imagine a child and a parent playing catch. The child throws the ball, and the parent catches it. The parent then throws it back. They continue this process, waiting for the ball to be caught before throwing it again.

In an error-free channel, this works smoothly because every throw (data packet) is perfectly caught (received). The sender sends one data packet and waits for the receiver to acknowledge it before sending the next one. This ensures every packet is received correctly.

Stop and Wait for Noisy Channels:

Now, imagine the same game of catch, but it's foggy and hard to see. The child might not catch the ball every time. If the ball is missed, the parent must throw it again.

In noisy channels, errors can occur, so the stop-and-wait protocol includes mechanisms to detect and correct errors. If the sender doesn’t receive an acknowledgment within a certain time, it resends the packet. This ensures that despite errors, every data packet eventually reaches the receiver correctly.

19. Explain the One-Bit Sliding Window Protocol

The one-bit sliding window protocol is a way of sending and receiving data between two devices. Imagine two friends passing a single book back and forth. The sender (friend 1) sends a page of the book (a packet) to the receiver (friend 2).

1. Sending Data: Friend 1 sends one page at a time.
2. Receiving Data: Friend 2 reads the page and then sends an acknowledgment (like a thumbs-up) back to Friend 1.
3. Next Page: Only after getting the thumbs-up, Friend 1 sends the next page.

This ensures that each page is received correctly before moving on to the next. If Friend 2 doesn't send a thumbs-up, Friend 1 will know there was an issue and resend the page.

20. Difference Between Go-Back-N and Selective Repeat Protocols

Both Go-Back-N and Selective Repeat protocols are ways to manage data transfer between devices, but they handle errors differently.

Go-Back-N Protocol

• Imagine a teacher handing out homework pages to students.
• If a student finds an error on one page, the teacher takes back all the pages given after that error and rechecks them.
• The teacher starts handing out pages again from the error point.

In Go-Back-N, if a packet is lost or corrupted, the sender goes back and resends that packet and all the following packets, even if some were correctly received.

Selective Repeat Protocol

• Think of a librarian lending out books to readers.
• If a reader finds a missing page, the librarian only replaces that specific page, not the whole book.

In Selective Repeat, only the lost or corrupted packet is resent, and correctly received packets are not retransmitted.

21. Describe Concurrent Logical Channels

Concurrent logical channels allow multiple conversations to happen simultaneously over the same physical connection.

Imagine a large conference call with multiple discussion rooms. Even though everyone is on the same call (same network), different groups (logical channels) can discuss different topics without interfering with each other.

1. Multiple Topics: Each group can discuss their topic independently.
2. Shared Line: Everyone uses the same phone line but can focus on their conversation.
3. Efficient Communication: This setup allows for better use of the phone line, as multiple discussions can happen at once without confusion.

In computer networks, concurrent logical channels help to manage different data streams efficiently, ensuring smooth and organized communication.

22. Explain Go-Back-N Protocol

Go-Back-N protocol is a method used in computer networks to ensure data is sent correctly. Imagine you are playing catch with a friend, and you are throwing a series of balls to them. Each ball represents a packet of data.

1. Sending Multiple Packets: You throw several balls (packets) in a row without waiting for your friend to catch each one. For example, you throw balls numbered 1 to 5 quickly.
2. Acknowledgment: Your friend catches the balls and shouts back the number of the last ball they caught correctly. If they catch ball 3, they shout "3".
3. Error Handling: If they miss ball 4, they won't shout "4" or "5". You realize they missed a ball and need to resend balls 4 and 5. This ensures your friend gets all the balls in the right order. You have to go back and resend from the missed ball onwards, hence the name "Go-Back-N".

23. Describe the Selective Repeat Protocol

Selective Repeat protocol is another method for ensuring data is sent correctly over a network. Imagine you are playing catch again, but this time with a twist.

1. Sending Multiple Packets: You throw several balls (packets) in a row, just like before. You throw balls numbered 1 to 5.
2. Acknowledgment: Your friend catches the balls and shouts back the number of each ball they caught. They can say "1, 2, 3", indicating they caught balls 1, 2, and 3 correctly.
3. Error Handling: If they miss ball 4 but catch ball 5, they shout "1, 2, 3, 5". You now know they missed ball 4. Instead of resending all the balls from 4 onwards, you only resend ball 4. This way, only the missed ball is resent, making the process more efficient.

Real-Life Example Comparison

• Go-Back-N Protocol: Imagine you're handing out homework assignments to students in a line. If a student drops their assignment, you go back and re-hand out assignments starting from the one they dropped.
• Selective Repeat Protocol: Imagine you're handing out numbered tickets to a group of people. If someone loses their ticket, you only give them a replacement for the lost one, without reissuing the other tickets.

Both protocols aim to ensure that data is received accurately, but Selective Repeat is more efficient as it only resends the missing data rather than starting over from the error.