.NET Architecture & System Design Interview Question #132

What is the Fallback pattern?

Resilience, Rate Limiting, Health Checks & Observability Senior Advanced

Quick Interview Answer

Fallback provides an alternative response or behavior when the preferred dependency or operation is unavailable. Examples include cached data, a reduced feature set, or a safe default.

Detailed Explanation

Fallback provides an alternative response or behavior when the preferred dependency or operation is unavailable. Examples include cached data, a reduced feature set, or a safe default.

Fallback is appropriate only when the alternative remains correct enough for the business scenario. Returning misleading or unsafe data merely to avoid an error is not a valid resilience strategy.

Code Example

Recommendation service fails
        |
Fallback:
show product page
without recommendations

Core purchase path remains available.