Which of the following security mechanisms prevents illegal access to a computer network by verifying the identity of a user or device?

Authentication is the security mechanism that verifies the identity of a user or device before granting access to a computer network.
It ensures that only authorized individuals or systems can log in or connect.
Common methods include:
Passwords / PINs
Biometric verification (fingerprint, face recognition)
Multi-factor authentication (MFA) (e.g., password + OTP)
Digital certificates / tokens
Key Takeaway
Authentication is the first line of defense in network security, preventing illegal access by confirming “who you are” before allowing entry.