Which IP header field indicates how far a datagram has been fragmented?

Which IP header field indicates how far a datagram has been fragmented?

• A. Fragmentation Offset
• B. Total Length
• C. Identification
• D. Flags

Answer: (A)

When a datagram is broken into fragments, each piece must be reassembled in the correct order. The field that tells where this fragment’s data fits in the original payload is the Fragment Offset. It indicates the starting position of the fragment’s data within the original datagram and is measured in 8-byte units. This offset, together with an Identification value (which groups all fragments from the same original datagram) and the More Fragments flag (which tells whether more fragments follow), lets the receiver reconstruct the full message. The other header fields play different roles: the Identification field groups fragments from the same datagram; the Flags field (especially the More Fragments bit) signals if additional fragments exist; and the Total Length field shows how long this particular fragment is, not where it belongs in the original payload.

When a datagram is broken into fragments, each piece must be reassembled in the correct order. The field that tells where this fragment’s data fits in the original payload is the Fragment Offset. It indicates the starting position of the fragment’s data within the original datagram and is measured in 8-byte units. This offset, together with an Identification value (which groups all fragments from the same original datagram) and the More Fragments flag (which tells whether more fragments follow), lets the receiver reconstruct the full message.

The other header fields play different roles: the Identification field groups fragments from the same datagram; the Flags field (especially the More Fragments bit) signals if additional fragments exist; and the Total Length field shows how long this particular fragment is, not where it belongs in the original payload.