A penetration tester runs a network scan but has some issues accurately enumerating the vulnerabilities...

[Reference: CompTIA PenTest+ PT0-003 Official Study Guide - "Network Scanning and Fingerprinting Challenges", Incorrect options:, Option A (Firewall block rule): A firewall may block the scan, but typically it would result in no response rather than an "OS identification failed" message., Option B (Outdated scanner database): While an outdated database might miss vulnerabilities, it does not directly cause OS detection failure., Option C (False positive): A false positive refers to incorrect detection, but this is an OS detection failure, not a misidentified OS., ]