A late collision indicates that another system attempted to transmit after a host has transmitted at least the ______ bytes of its frame

• A. First 128 bytes of the frame
• B. Preamble
• C. First 64 bytes of the frame
• D. Last 64 bytes of the frame

Answer: (C)

In Ethernet networks that use CSMA/CD, devices listen before transmitting and detect collisions by sensing the line. To ensure a collision is detected while the first transmitter is still sending, Ethernet defines a minimum frame size. For traditional 10 Mbps Ethernet, that minimum is 64 bytes. If a second device starts transmitting after those first 64 bytes have already been sent, a collision can occur later in the frame; that is called a late collision. So the statement is referring to the first 64 bytes of the frame. The preamble is used for synchronization and isn’t counted toward the frame length that determines early vs late collisions, and the other options don’t match this standard 64-byte threshold.