Explanation From HCIA-Security documents:
Antivirus software relies heavily on its signature database to identify known malware, suspicious files, and malicious behaviors. Because new threats appear continuously and existing malware is frequently modified to evade detection, the signature library must be updated very often to keep protection effective. Updating every day is the best practice in most enterprise and personal environments, and many antivirus products actually update multiple times per day automatically.
If signatures are updated only monthly , half-monthly , or every three months , there is a large window where newly released malware samples and variants will not be recognized, increasing the chance of infection and successful compromise. Daily updates reduce this exposure window and ensure the antivirus engine has the newest detection patterns, reputation indicators, and sometimes updated heuristic rules released by the vendor.
In addition, daily updates align with operational security expectations: endpoints are exposed to internet content, email attachments, removable media, and downloads on a constant basis, so outdated signatures quickly become a weak link. Therefore, the correct answer is Every day .
