Which of the following is used in the options field of IPv4 ?

Answer: All of the above

Explanation: The IPv4 header includes an optional 'options' field that can carry various control or recording information. The given items are all standard examples of IPv4 options:

• Strict source routing: Specifies an exact sequence of intermediate IP addresses that the packet must follow.

• Loose source routing: Provides a list of intermediate addresses that should be visited but allows other hops between them.

• Timestamp: Records timestamps (and optionally the router addresses) as the packet traverses the network.

Note: IPv4 options exist but are infrequently used in modern networks because they add processing overhead and can create security concerns.