The default preset after a device fails. For example, an electric door auto-locks in the event of a failure.

Fail Closed

Failure mode in which the system defaults to a closed state.

Fail Open

Systems that default into an open state. Done to prevent a device from becoming a Single Point of Failure.

  • Firewall (sometimes)
  • ACL (sometimes)
  • IPS (sometimes)
  • Network Tap Fail open is risky, and is not the default option for devices.