Block IP address

If you want to prevent that your form is submitted multiple times from same IP address, you can set unique submissions on a form. Inside of this guide you can find how to do it: 

https://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form 

You can set Strict Check which controls the IP address.

If you want to achieve something else, please provide us more details about what you are trying to achieve? 

Let us know if you need further assistance.