Comprehensive and Detailed Explanation From Exact Extract:
A fail-open configuration means that if the firewall experiences an outage or failure, traffic is allowed to pass through rather than being blocked. This design decision directly prioritizes availability over other security principles.
The CIA Triad (Confidentiality, Integrity, Availability) is central in SY0-701. A fail-open firewall risks allowing unauthorized or malicious traffic during a failure, sacrificing security controls in order to maintain service uptime. This is typically used in environments where interruptions are unacceptable, such as:
Public-facing websites
Critical customer applications
Healthcare systems
Financial transaction portals
Fail-closed configurations, in contrast, prioritize confidentiality and integrity by blocking traffic when a failure occurs.
Because the organization chose fail-open, it demonstrates that maintaining continuous access to the website is more important than preventing potential exposure. This approach is aligned with the Availability pillar of the CIA model.
The SY0-701 exam emphasizes this design choice under General Security Concepts, specifically in resilience, failover mechanisms, and risk-based decisions when selecting fail-open vs. fail-closed strategies.
