In TCP, which feature helps prevent congestion and packets loss?

The feature that helps prevent congestion and packet loss in TCP is the sliding window mechanism. TCP uses the sliding window technique to manage the flow of data between sender and receiver, allowing the sender to send multiple packets before needing an acknowledgment for the first packet.

This mechanism improves overall network throughput by enabling a more efficient use of the available bandwidth. The size of the window determines how many packets can be sent before waiting for an acknowledgment, and it dynamically adjusts based on current network conditions, including the rate of packet delivery and acknowledgment receipt. When the network congestion is detected, TCP can reduce the window size to lower the amount of data in transit, thereby decreasing the chance of congestion and packet loss.

The other features listed, such as forwarding, checksum, and packet header, serve different purposes in networking. Forwarding is about directing packets to their appropriate destinations, checksum is used for error-checking to ensure data integrity, and the packet header contains control information for the packet but does not directly manage congestion. Thus, sliding window is specifically designed to address congestion control in TCP.