What is the typical MTU for Ethernet and does it include headers?

• A. 1500 bytes; it excludes headers and payload
• B. 1518 bytes; it includes preamble
• C. 1400 bytes; it includes headers and preamble
• D. 1500 bytes; it refers to the maximum frame size including headers, excluding preamble and IFG

Answer: (D)

Ethernet MTU is the maximum payload that can be carried in one Ethernet frame, typically 1500 bytes. This size corresponds to the IP packet inside the frame, not including the Ethernet header (14 bytes) or the Frame Check Sequence (4 bytes). If you count everything that goes on the wire for that frame, the total can be 1518 bytes: 14 bytes of header plus 1500 bytes of payload plus 4 bytes of FCS. The preamble (used for synchronization) and the inter-frame gap are not part of the frame size counted by the MTU. So the typical MTU is 1500 bytes, referring to the payload inside the frame (excluding preamble and IFG); the full on‑wire frame can be 1518 bytes when you include the header and FCS.