Which field in an Ethernet frame is used to verify that the received frame contains no errors?

The Frame Check Sequence (FCS) is a 4-byte field at the end of an Ethernet frame that contains a Cyclic Redundancy Check (CRC) value. The sender calculates the CRC over the frame data and stores it in the FCS; the receiver performs the same calculation and compares results to verify integrity. A mismatch indicates a corrupted frame, which is then discarded.

The type field (EtherType) identifies the upper-layer protocol encapsulated in the frame, such as IPv4 (0x0800) or ARP (0x0806), and performs no error checking.

The preamble is a 7-byte synchronization sequence used to signal the start of a frame to the receiver and does not carry any error-detection information.

Segment is not a field in the Ethernet frame structure; it is a term used at the TCP transport layer.

Protocol is not a named field in the standard Ethernet II frame; the nearest equivalent is the EtherType/type field, which identifies the payload protocol rather than verifying integrity.