What is the byte size of the 'SFD' in an Ethernet header?

The Start Frame Delimiter (SFD) in an Ethernet header is 1 byte in size. This 1-byte field is crucial in the Ethernet frame structure as it indicates the start of the frame data. Following the preamble, which is used for synchronization, the SFD signifies that the payload data is about to begin, allowing the receiving device to distinguish between the preamble and the actual frame content.

In standard Ethernet frames, the structure comprises several components, including the Destination MAC address, Source MAC address, EtherType/length, and the data/payload with a Frame Check Sequence. The SFD specifically plays the role of signaling the end of the preamble and is essential for the correct interpretation of the incoming frames. Understanding the function and size of the SFD is key for network professionals as it directly relates to proper packet handling in Ethernet communication.