ITPEC IP October 2018 Question 45

Continuing processing when a fault occurs is fault tolerance — the only option that pairs a reliability term with its own definition.

• •Fault tolerance: the system keeps processing despite a fault, typically through redundant components, possibly with reduced function.
• •Fail-safe: when a fault occurs, the system is brought to a safe state to minimize damage (for example, traffic lights all turn red).
• •Fail-soft: the faulty part is cut off and the system continues with reduced function.
• •Foolproof: the design keeps people from making mistakes, or makes a mistake harmless.
• •Fault avoidance: high-quality, high-reliability parts make faults rare in the first place.

Answer (c)

Why not others:

• •(a) — keeping the system in a safe state to minimize damage after a fault is fail-safe, not foolproof
• •(b) — lowering the probability of faults with high-reliability parts is fault avoidance, not fail-safe
• •(d) — designing so that humans do not make mistakes, or mistakes cause no failure, is foolproof, not fail-soft

Key rule: Fault avoidance keeps faults from happening; fault tolerance keeps the system working when they do, by stopping safely (fail-safe) or running with reduced function (fail-soft); foolproof guards against human error.

System Component · AI-written, may contain errors