A packet has arrived with an M bit value of 1. Is this the first fragment, the last, or a middle fragment? Do we know if the packet was fragmented?

Now you’re given a packet where the M bit (More Fragments flag) = 1. Let’s figure out what that tells you.

The M bit indicates whether more fragments are coming after this one.
If M = 1, it clearly means more fragments are still on the way.

So one thing becomes certain right away.
This packet is not the last fragment.

Now the next question. Is it the first fragment or a middle fragment?

Here’s the catch.
You cannot decide that using the M bit alone.

To know whether it’s the first or middle fragment, you need the fragment offset.

• If offset = 0 and M = 1, then this is the first fragment

• If offset > 0 and M = 1, then this is a middle fragment

So the M bit tells you about continuation, but not position.

Final Interpretation

• M = 1 always means fragmentation has occurred

• It confirms this is not the last fragment

• You need the offset field to distinguish between first and middle fragment

Case	M Bit	Fragment Offset	Interpretation	Was Fragmented?
Case 1	1	0	First fragment	Yes
Case 2	1	> 0	Middle fragment	Yes