Why are high-volume port scans often ignored by defenders?

• A. It Is Benign Traffic That Requires No Action
• B. It Is From Trusted Sources
• C. It Is Encrypted
• D. There Is No Actionable Defense To Execute

Answer: (D)

High-volume port scans are reconnaissance signals—they probe what services are open and what could be targetable, but they don’t by themselves expose a vulnerability that can be fixed with a single action. Because such scans come from many sources (threat actors, researchers, or compromised hosts) and often don’t indicate an actual breach, there isn’t a clear, universal defense to execute solely in response to them. Taking sweeping blocking or remediation actions for every scan can create false positives, disrupt legitimate activity, or simply not reduce risk, since the real danger often lies in what happens after scanning—namely, targeted, follow-up attempts or exploiting specific weaknesses. The practical approach is to monitor, correlate with other signals, and harden defenses, rather than acting on the scan alone.

The other ideas don’t fit as well because scans aren’t inherently benign or trustworthy enough to justify no action, sources aren’t reliably trusted, and the scanning traffic isn’t something that becomes meaningless because it’s encrypted.