What does a reactive approach focus on in network security?

A reactive approach in network security primarily emphasizes detecting and responding to attacks after they have already taken place. This method contrasts with proactive strategies, which focus on preventing attacks before they happen.

In a reactive stance, organizations rely on monitoring and incident response mechanisms to identify security breaches or incidents as they occur, allowing them to mitigate damage and recover more effectively. This includes employing various detection tools that analyze logs and network traffic for signs of compromise, as well as establishing protocols for immediate response once an incident is detected.

The other options relate to preventive or protective measures rather than responsive actions. For instance, preventing attacks before they occur aligns with a proactive approach and would involve implementing security measures such as firewalls and intrusion prevention systems. Similarly, blocking all unauthorized access and encrypting data before transmission represent strategies aimed at securing the network and data from potential threats before they materialize, thereby not fitting the definition of a reactive approach.