Why does each IP packet contain a sequence number?

Why does each IP packet contain a sequence number?

• A. To determine the original order of the packets.
• B. To identify the sender's device.
• C. To indicate the total number of packets in the transmission.
• D. To encrypt the payload.

Answer: (A)

The idea being tested is how data that’s split into packets can be put back together correctly. Packets may take different routes and arrive at different times, so the numbers that label each piece of data let the recipient place the bytes in the original order and notice if any piece is missing. That way the whole message can be reconstructed reliably, even if packets don’t arrive in sequence. It’s not about identifying the sender’s device—that’s handled by the address information. It’s not about indicating how many packets were sent—the receiver doesn’t rely on a total count to reassemble. And it’s not about encryption—the sequence helps with order, not with encrypting the payload.

The idea being tested is how data that’s split into packets can be put back together correctly. Packets may take different routes and arrive at different times, so the numbers that label each piece of data let the recipient place the bytes in the original order and notice if any piece is missing. That way the whole message can be reconstructed reliably, even if packets don’t arrive in sequence.

It’s not about identifying the sender’s device—that’s handled by the address information. It’s not about indicating how many packets were sent—the receiver doesn’t rely on a total count to reassemble. And it’s not about encryption—the sequence helps with order, not with encrypting the payload.