Question: Internet packet data structure consists of I. source address II. destination address III. serial number of packets IV. message bytes V. Control bits for error checking VI. Path identification bits

Answer:

The item that is not typically part of the Internet packet data structure is:
III. Serial number of packets

While the source address (I), destination address (II), message bytes (IV), control bits for error checking (V), and path identification bits (VI) are commonly included in the packet data structure, the serial number of packets (III) is not typically part of the standard Internet packet structure. Serial numbers or sequence numbers may be used in higher-level protocols or within specific applications to ensure the correct ordering or delivery of packets, but they are not a universal component of the basic Internet packet structure.