Which switching method has the lowest level of latency?

• A. Cut-Through
• B. Store-and-Forward
• C. Fragment-Free
• D. Fast-Forward

Answer: (D)

Latency in switching is determined by when the switch starts forwarding a frame. Fast-Forward minimizes this by beginning to forward as soon as enough header information is available to decide the output port, typically after reading the destination MAC address. Because the switch doesn’t wait for the rest of the frame or perform a full CRC check before forwarding, the frame exits the switch with the smallest delay.

Store-and-Forward, by contrast, waits for the entire frame to arrive and for CRC verification before forwarding, which adds noticeable delay. Fragment-Free sits in between, forwarding after the first 64 bytes to reduce the chance of sending runt frames while still not matching the absolute earliest forwarding. Cut-Through also forwards early after reading the destination address, but Fast-Forward represents the fastest point at which forwarding can commence, hence the lowest latency.