CSMA/CA protocol in Computer Networks - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

How does CSMA/CA avoid collisions?

In the CSMA/CA protocol, what is the main method used to avoid data collisions on a network?

A It sends data and waits for a collision signal to resend.

B It sends data immediately without checking the channel.

C It uses a token passing system to control who sends data.

D It listens to the channel and waits for it to be free before sending data.

💡 Hint

Think about how the device checks the channel before sending.

CSMA/CA listens to the channel first and only sends data if the channel is free, helping to avoid collisions.

📋 Factual

intermediate

What does CSMA/CA stand for?

What is the full form of CSMA/CA?

A Carrier Sense Multiple Access with Collision Avoidance

B Carrier Sense Multiple Access with Collision Arbitration

C Carrier Signal Multiple Access with Collision Avoidance

D Carrier Sense Multiple Access with Collision Acknowledgment

💡 Hint

Focus on the words related to sensing and avoiding collisions.

CSMA/CA stands for Carrier Sense Multiple Access with Collision Avoidance, describing how devices sense the channel and avoid collisions.

🔍 Analysis

advanced

Why is CSMA/CA preferred over CSMA/CD in wireless networks?

Compare CSMA/CA and CSMA/CD. Why is CSMA/CA more suitable for wireless networks?

A Because CSMA/CA uses a token system which is better for wireless.

B Because CSMA/CD requires more power which wireless devices lack.

C Because wireless devices cannot detect collisions easily, so avoiding collisions is better.

D Because CSMA/CD works only with fiber optic cables.

💡 Hint

Think about how devices detect collisions in wired vs wireless networks.

Wireless devices cannot easily detect collisions due to signal limitations, so CSMA/CA avoids collisions before sending data, unlike CSMA/CD which detects collisions after they happen.

🚀 Application

advanced

What happens if two devices send data simultaneously in CSMA/CA?

In CSMA/CA, if two devices sense the channel is free and send data at the same time, what mechanism helps reduce the chance of collision?

A Random backoff timers delay retransmission to avoid repeated collisions.

B Devices switch to a different channel automatically.

C Devices use a fixed wait time before resending data.

D Devices immediately resend data without delay.

💡 Hint

Consider how devices avoid sending again at the same time after a collision.

CSMA/CA uses random backoff timers so devices wait different random times before trying again, reducing repeated collisions.

❓ Reasoning

expert

How does the RTS/CTS mechanism improve CSMA/CA performance?

Explain how the RTS/CTS (Request to Send / Clear to Send) mechanism works in CSMA/CA and why it improves network performance.

A It speeds up data transmission by sending data without waiting.

B It reserves the channel before sending data, reducing collisions especially in hidden node situations.

C It encrypts data to prevent unauthorized access.

D It increases the signal strength to reach farther devices.

💡 Hint

Think about how devices coordinate before sending data to avoid hidden node problems.

RTS/CTS lets a device ask permission to send data and waits for a clear signal, which helps avoid collisions caused by devices that cannot hear each other (hidden nodes).