Designing Reliable Systems :Reliable Google Cloud Infrastructure: Design and Process (Preparing for Google Cloud Certification: Cloud Architect Professional Certificate) Answers 2025

Question 1

You’re creating a service and want to protect it from overload caused by many client retries.

❌ Lazy caching
🟩 Truncated exponential backoff
❌ Circuit breaker
❌ Overload feedback repudiation

Explanation:

Truncated exponential backoff is the correct pattern to slow down retries during outages.
It prevents clients from retrying too aggressively and overwhelming your service.

Question 2

You need a relational DB with 99.999% availability and survives regional outages.

❌ BigQuery
🟩 Spanner
❌ Firestore
❌ Cloud SQL

Explanation:

Cloud Spanner provides:

• Global distribution

• Strong consistency

• 99.999% availability SLA

• Survives regional failures

Cloud SQL cannot survive a regional outage. Firestore is NoSQL. BigQuery is not a relational OLTP DB.

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