Which of the following statements is TRUE?
2006
Which of the following statements is TRUE?
Answer: C. Ethernet frame includes a CRC field and IP packet includes a checksum field — Correct statement: Ethernet frame includes a CRC field and IP packet includes a checksum field. Ethernet frame (link layer): Contains a Frame Check Sequence…
- A.
Both Ethernet frame and IP packet include checksum fields
- B.
Ethernet frame includes a checksum field and IP packet includes a CRC field
- C.
Ethernet frame includes a CRC field and IP packet includes a checksum field
- D.
Both Ethernet frame and IP packet include CRC fields
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Correct answer: C
Correct statement: Ethernet frame includes a CRC field and IP packet includes a checksum field.
Ethernet frame (link layer): Contains a Frame Check Sequence (FCS), which is a 4-byte CRC (CRC-32) placed in the trailer to detect transmission errors for the entire frame (except preamble and FCS field).
IP packet (network layer): IPv4 includes a 16-bit header checksum (ones' complement) that covers only the IP header, not the payload. IPv6 does not include a header checksum.
Implications and common confusions: Do not confuse CRC and checksum: CRC is used at the link layer (Ethernet) as FCS, while the IP-level checksum (IPv4) is simpler and header-only. Modern protocols also rely on transport-layer checksums (TCP/UDP) for end-to-end integrity.
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