Assume that you posted something on the website using a computer in the lab. That website does not require login but it recorded your IP address. Is it possible for other people to discover that you are a person who posted it by tracking back the IP address? Will that be different if you posted from your mobile phone over the cellular network?
Hint: Which IP address will be recorded by the website, local or public? Is there any record somewhere showing that you occupied that IP at that time.