A systems administrator receives notification about unauthorized access to company resources outside normal business hours. Which of the following security measures should the systems administrator…

Perimeter firewalls control network traffic at the boundary, but they typically allow access for legitimate credentials. If an attacker possesses valid credentials, a firewall alone will not prevent them from accessing internal resources.

SSL-enabled DNS (DNS over HTTPS/TLS) encrypts DNS queries to enhance privacy and prevent DNS manipulation, but it does not directly prevent unauthorized login attempts to company resources using compromised credentials.

Anonymizing VPNs are used to obscure a user's IP address and internet activity, which is generally not a security measure an organization would implement for its own resources to prevent unauthorized access; rather, it makes tracking legitimate and illegitimate access more difficult.

Multifactor authentication (MFA) requires users to provide two or more different authentication factors (e.g., something you know like a password, something you have like a token or phone, something you are like a fingerprint). This significantly prevents unauthorized access even if an attacker manages to obtain a user's password because they would still lack the second factor.