When deploying an Intrusion Prevention System (IPS) the BEST way to get maximum protection from the system is to deploy it

An Intrusion Prevention System (IPS) is designed to actively block malicious activity in real-time. To achieve this, it must be deployed "in-line," meaning it sits directly in the path of network traffic. In this position, it can inspect all incoming and outgoing packets. When a threat is identified based on its rule set, the IPS can take immediate preventative action, such as dropping the malicious packets, which is known as "blocking mode." This configuration provides the maximum level of protection by stopping attacks before they can reach their intended targets.

A. Promiscuous mode is a passive monitoring method used by Intrusion Detection Systems (IDS) and does not allow for the blocking of traffic.
C. A device in promiscuous mode cannot block traffic because it is not in the direct path; it only receives a copy of the traffic.
D. Alert mode in an in-line deployment only warns of malicious traffic but does not stop it, functioning as an in-line IDS, not an IPS.

1. National Institute of Standards and Technology (NIST). (2012). Guide to Intrusion Detection and Prevention Systems (IDPS) (NIST Special Publication 800-94, Revision 1). Section 3.2, "Intrusion Prevention System (IPS) Technologies," Page 3-3. "IPS technologies are deployed in-line on a network connection and have the ability to block or reject traffic based on its security characteristics."

2. Stallings, W. (2017). Cryptography and Network Security: Principles and Practice (7th ed.). Pearson. (University courseware textbook). Chapter 21, "Intruders," discusses the distinction between IDS (passive monitoring) and IPS (in-line prevention).