What does a node do before transmitting packets under Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)?

In the context of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), before a node transmits packets, it must first determine if the communication channel is clear. This is achieved through the process known as "carrier sensing," where the node listens to the medium to detect if another device is currently transmitting. By waiting for the media to be clear, the node helps to avoid collisions that would occur if multiple nodes attempted to transmit simultaneously.

Once the node determines that the channel is unobstructed, it can proceed with the transmission of its packets. This method is particularly effective in wireless networks, where the risk of collisions is high due to the shared nature of the communication medium.

The other choices do not accurately reflect the process described by CSMA/CA. For instance, while waiting for a random interval can be part of the overall protocol in terms of backoff strategies, it is not the primary action taken before checking the medium's status. Similarly, avoiding media congestion refers more generally to network management techniques rather than the initial steps of packet transmission in this specific protocol. Monitoring signal strength, while useful for assessing connection quality, does not play a role in the initial decision to transmit under CSMA/CA.