Q: What is used to determine when the communications channels are clear and when a device is free to transmit data?
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Q: Whether a device is free to transfer data, how is it determined whether the communications channels are clear?
- Internet Protocol (IP)
- Transmission Control Protocol (TCP)
- Ethernet
- Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
Explanation: The Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol is used to identify whether the communication channels are clear and when a device is free to send data. CSMA stands for Carrier Sense Multiple Access, while CD stands for Collision Detection. CSMA/CD is most often linked with classic Ethernet networks that run on a shared communication channel, such as coaxial wires. These networks typically use Ethernet.
Before sending any data, a device that uses the CSMA/CD protocol “listens” to the channel that is being used for communication. If there are no obstructions in the channel, the broadcast will continue. If two devices try to transmit at the same time and a collision occurs, CSMA/CD will identify the collision and start a backoff period before the devices try to communicate again. This will prevent further collisions from occurring. Full-duplex communication is used often in modern Ethernet networks; hence, CSMA/CD cannot be used in these kinds of environments.
