Medium Access Control (MAC) MCQs (1-9)

A wireless LAN has multiple stations trying to send data simultaneously. To minimize collisions, each waits for a random backoff time before transmitting. Which MAC protocol is being used?

• Token Passing

• CSMA/CA

• CSMA/CD

• ALOHA

In a wired Ethernet LAN, two nodes start transmitting at the same time. Both detect the collision and stop transmission immediately. Which mechanism helps them resume transmission later?

• Token rotation

• Exponential backoff algorithm

• Round-robin scheduling

• RTS/CTS exchange

A network uses a logical ring structure where only one station can transmit at a time using a special control frame. Which MAC protocol does this describe?

• Slotted ALOHA

• Token Passing

• CSMA/CD

• Polling

A Wi‑Fi access point allows only one device to send data at a time. Before transmission, the device checks the channel and sends RTS, waiting for CTS before proceeding. This mechanism prevents:

• Hidden terminal problem

• Capture effect

• Congestion

• Bandwidth wastage

A satellite link has high propagation delay. Using pure ALOHA results in heavy collisions. Which protocol would improve throughput?

• CSMA/CD

• Slotted ALOHA

• Token Ring

• CDMA

A company wants to connect 30 computers with minimal delay and fairness in transmission. Token ring is considered. The token gets lost frequently due to hardware issues. What is the main impact?

• Increased collisions

• Starvation

• Network halts until token is regenerated

• Hidden terminal problem

In a wireless sensor network, nodes share a single channel but have limited energy. Which MAC approach minimizes idle listening and collisions?

• CSMA/CD

• TDMA

• Slotted ALOHA

• Token passing

Which statement best contrasts CSMA/CA and CSMA/CD for wireless vs. wired links?

• CSMA/CD is preferred in Wi‑Fi because collisions are rare in wireless

• CSMA/CA avoids collisions proactively; CSMA/CD detects collisions after they occur

• Both require token passing to arbitrate channel access

• CSMA/CA and CSMA/CD are identical except for frame size

An Ethernet frame with a corrupted CRC field reaches the destination. What happens?

• Frame is accepted and corrected

• Frame is discarded silently

• Frame is retransmitted automatically

• Frame is stored for analysis

A network administrator observes multiple stations backing off repeatedly in a busy Ethernet LAN. What could be the cause?

• Hidden terminals

• High collision rate

• Token loss

• Congested switch buffer