Solution

The correct answer is Option 2) A, B and D Only

Key Points

• Controlled-access protocols: Controlled-access protocols are mechanisms used in networking to ensure that only one device transmits at a time on a shared communication medium. Such protocols prevent collisions and ensure orderly communication.
• Reservation: ✅ Reservation is a controlled-access protocol where a station reserves the right to use the medium in advance. This avoids collisions and ensures that the reserved station gets exclusive access during its turn.
• Polling: ✅ Polling is a controlled-access protocol where a primary station controls access to the medium. It polls secondary stations one at a time to check if they have data to send, ensuring orderly communication.
• TDMA: ❌ Time Division Multiple Access (TDMA) is not a controlled-access protocol. It is a channel access method that divides the channel into time slots, assigning each user a specific time slot. It is not dynamically controlled during transmission.
• Token Passing: ✅ Token Passing is a controlled-access protocol where a token circulates in the network. A station can transmit only when it holds the token, ensuring controlled access to the medium.
• CSMA/CA: ❌ Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is not a controlled-access protocol. It is a contention-based protocol where devices compete for access to the medium, and collisions are avoided using backoff mechanisms.

Additional Information

• Controlled-access protocols: These protocols are efficient in preventing collisions but may introduce some delay due to the need for control mechanisms like polling or token passing.
• Contention-based protocols: Protocols like CSMA/CA are simpler to implement but may lead to collisions, especially in high-traffic networks.

Hence, the correct answer is: Option 2) A, B and D Only