Someone recently asked me about for ideas on how to prevent students from sharing Packet Tracer activity solutions. Just in case you don't know or remember, I believe the User Profile feature in PT may have been implemented with this in mind.

Here are some suggestions you can try:

Instruct students to edit the User Profile (Options, User Profile) and insert their name and email address and a description of some sort (do not specify). This will allow you to easily identify the author of the assignment via three different fields.

Tell students you will not accept a completed assignment unless they configure the user profile as described above

If students share the file and the recipient modifies the user profile, which they will have to do for you to accept the completed assignment, the activity will reset and their configuration will revert to the initial network, whatever it was. They are warned about this when they make the profile change.

Students can still share the configurations by doing screen captures, but depending on the complexity of the activity and configuration, they will need to share a lot of images to cover the entire assignment, which may dissuade them from attempting.

This is this is configured in the Activity Wizard under Initial Network/Locking/Starting items/Activity/Reset Activity, in case you want to create your own activities. Remember to configure a password so that students cannot change the Reset Activity option to bypass this feature.

I hope this helps and if it works for you, be sure to share this with your instructors.