Which QoS parameter might most concern us considering the Internet's "best effort" delivery nature?

The primary concern regarding the Internet's "best effort" delivery nature is packet loss. In a best effort network, there are no guarantees on the quality or delivery of packets, which means packets can be lost during transmission due to network congestion or other issues. This unpredictability can severely impact applications that rely on consistent data delivery, such as voice over IP (VoIP) or video streaming.

Packet loss can lead to interruptions in service and degraded quality, making it a critical parameter to monitor and manage in Quality of Service (QoS) strategies. Network engineers and technicians need to be aware of this risk when designing and maintaining networks to ensure optimal user experiences.

The other parameters, such as throughput, delay, and jitter, while important, do not directly reflect the reliability and consistency of data delivery in the same manner that packet loss does.