The Fragment Offset field is how many bits wide?

The Fragment Offset field is how many bits wide?

• A. 12 bits
• B. 13 bits
• C. 14 bits
• D. 16 bits

Answer: (B)

In IPv4, the Fragment Offset field tells you where a fragment’s payload fits within the original datagram. It’s expressed in units of eight bytes, which means each value references eight-byte blocks rather than individual bytes. The field is 13 bits wide because the 16-bit combined field that carries both this offset and the Flags uses 3 bits for Flags and the remaining 13 bits for the offset. That gives offsets from 0 up to 8191 (0 to 8191 × 8 bytes), which allows describing the position of fragments while staying within the overall 65,535-byte limit of an IP datagram (including the header). This structure enables proper reassembly at the destination, with the MF (More Fragments) flag indicating whether more pieces follow.

In IPv4, the Fragment Offset field tells you where a fragment’s payload fits within the original datagram. It’s expressed in units of eight bytes, which means each value references eight-byte blocks rather than individual bytes. The field is 13 bits wide because the 16-bit combined field that carries both this offset and the Flags uses 3 bits for Flags and the remaining 13 bits for the offset. That gives offsets from 0 up to 8191 (0 to 8191 × 8 bytes), which allows describing the position of fragments while staying within the overall 65,535-byte limit of an IP datagram (including the header). This structure enables proper reassembly at the destination, with the MF (More Fragments) flag indicating whether more pieces follow.