Which type of security solution monitors the environment and takes automatic action against unauthorized access attempts?

An Intrusion Prevention System (IPS) is designed specifically to monitor network traffic and take immediate action against detected threats, such as unauthorized access attempts. The IPS operates in real-time, ensuring that if it detects an intrusion or any suspicious activity, it can respond automatically by blocking the offending traffic, dropping malicious packets, or alerting administrators.

This proactive approach is what distinguishes IPS solutions from other security measures. While firewalls, such as stateful inspection firewalls and proxy firewalls, work primarily on filtering traffic based on predetermined rules without actively taking action against intrusions, an IPS goes a step further by identifying not only potential threats but also applying countermeasures dynamically.

In contrast, a Web Application Firewall (WAF) primarily focuses on protecting web applications by filtering and monitoring HTTP traffic for vulnerabilities specific to web applications. Its action is more about protecting applications from threats rather than taking direct preventive measures against network-level intrusions.

Hence, the selection of the IPS as the correct answer is based on its unique capability to automatically monitor and respond to unauthorized access attempts, making it a crucial component in proactive security postures.