Which field in the IPv4 header is specifically used to prioritize delay-sensitive network traffic?

The field in the IPv4 header that is specifically used to prioritize delay-sensitive network traffic is called Differentiated Services Code Point (DSCP). The DSCP is part of the Type of Service (ToS) field in the IPv4 header and is responsible for specifying the level of service and prioritization a packet should receive as it traverses the network.

By using this field, network devices can determine how to handle packets based on their urgency or requirements for low delay, high throughput, or other quality of service (QoS) metrics. In scenarios where delay-sensitive applications such as VoIP or video conferencing are involved, the DSCP values can enable routers and switches to treat these packets with higher priority compared to regular data traffic, ensuring that they receive the necessary bandwidth and are forwarded quickly, even under congestion.

The other fields in the IPv4 header serve different purposes. For instance, the Flags field is used to control fragmentation, the Internet Header Length (IHL) specifies the length of the header, and the Protocol field indicates the next level protocol encapsulated in the packet, none of which are directly responsible for prioritizing traffic like the DSCP field is.