According to your textbook, "So, how can we protect our Internet data from potential hackers?" is an example of a(n)

signpost

Explanation:

Since we are referring to literature, this would be an example of a signpost of the topic. Basically, by asking a question on the topic that was just read, you are helping the readers stay on track of the subject and making sure that they fully understand all the details of what they are reading. By asking such a question the readers reflect and think about the topic to answer the question, and if they do not know it they would go back and re-read the question so that they fully understand the topic to answer the question correctly.