What QoS mechanism is supported by the modified IP header ToS byte?

The correct answer is DiffServ, which stands for Differentiated Services. This QoS mechanism utilizes the modified Type of Service (ToS) byte in the IP header to enable the classification and management of network traffic based on various service requirements.

In DiffServ, the ToS byte contains six bits used for Differentiated Services Code Points (DSCP). These bits allow for differentiated forwarding treatment of packets, helping network devices, such as routers and switches, to apply different levels of service and prioritize traffic based on the defined policies. As a result, DiffServ is capable of managing the quality of service for various applications, ensuring that high-priority traffic can be transmitted with preferable performance characteristics.

Other options include mechanisms or protocols that do not directly use the modified IP header ToS byte for QoS management. IPSec is a suite of protocols used to secure Internet Protocol communications through authentication and encryption but does not handle QoS mechanisms through the ToS byte. 802.1Q is a networking standard that supports Virtual LANs (VLANs) and tagging in Ethernet networks, also separate from the QoS mechanisms found in DiffServ. RTP (Real-Time Protocol) is used for delivering audio and video over IP networks but does not employ