The misuse of public key, private key, and public/private key certificates poses significant security challenges to computer networks that are addressed by certificate monitoring. Certificate monitoring allows network administrators to detect and remedy poor security practices related to public key certificates and to detect and combat the malicious use of public key certificates in a centralized environment. Best practices and detection methods and systems are developed over time via machine learning to improve network security, and any detected misuse may be brought to a network administrator's attention or automatically remedied.