Cloud CDN integration in GCP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Architecture

intermediate

Designing a scalable Cloud CDN setup for a global website

You need to design a Cloud CDN integration for a website that serves users worldwide. Which architecture best ensures low latency and high availability?

A Use Cloud CDN directly without a load balancer, pointing to backend VMs in one region.

B Deploy multiple backend instance groups in multiple regions behind a global HTTP(S) Load Balancer with Cloud CDN enabled.

C Use a single backend instance group in one region with Cloud CDN enabled.

D Deploy backend instance groups in multiple zones within one region and enable Cloud CDN on each.

💡 Hint

Think about how Google Cloud distributes traffic globally and caches content close to users.

Option B uses a global HTTP(S) Load Balancer that routes user requests to the nearest backend region and enables Cloud CDN to cache content at edge locations worldwide, ensuring low latency and high availability.

❓ scaling

intermediate

Estimating cache hit ratio impact on backend load

Your Cloud CDN cache hit ratio improves from 60% to 90%. How does this affect the backend server load?

A Backend load decreases by 90% because all requests are served from cache.

B Backend load increases by 30% due to more cache misses.

C Backend load remains the same because cache hit ratio does not affect origin traffic.

D Backend load decreases by 30% because fewer requests reach the origin.

💡 Hint

Cache hit ratio means the percentage of requests served by the CDN cache instead of the backend.

Improving cache hit ratio from 60% to 90% means 30% more requests are served from cache, reducing backend load by that amount.

❓ tradeoff

advanced

Choosing between Cloud CDN and Cloud Storage for static content delivery

You have static assets stored in Cloud Storage. You want to serve them globally with low latency. What is the main tradeoff when enabling Cloud CDN in front of Cloud Storage?

A Cloud CDN adds caching and reduces latency but increases cost due to cache egress charges.

B Cloud CDN reduces cost but increases latency because it bypasses edge locations.

C Cloud CDN disables caching and serves content directly from Cloud Storage, increasing latency.

D Cloud CDN automatically compresses content but does not cache it, so no latency benefit.

💡 Hint

Consider how caching affects cost and performance.

Cloud CDN caches content at edge locations, reducing latency but may increase cost due to cache egress traffic charges.

🧠 Conceptual

advanced

Understanding cache invalidation in Cloud CDN

After updating your website content, you want Cloud CDN to serve the new version immediately. Which method correctly invalidates cached content?

A Use the Cloud CDN cache invalidation API to specify URLs to purge from cache.

B Wait for the cache TTL to expire; no manual invalidation is possible.

C Delete the backend instance group to clear the cache.

D Disable and re-enable Cloud CDN on the backend service.

💡 Hint

Think about how to remove specific cached content without downtime.

Cloud CDN provides an API to invalidate cached URLs immediately, ensuring updated content is served without waiting for TTL expiration.

❓ estimation

expert

Estimating required cache capacity for a high-traffic website

Your website receives 10 million requests per day. Average response size is 500 KB. You expect a 75% cache hit ratio. Estimate the daily data served from Cloud CDN cache edges.

A Approximately 10 TB per day served from cache edges.

B Approximately 5 TB per day served from cache edges.

C Approximately 3.75 TB per day served from cache edges.

D Approximately 1.25 TB per day served from cache edges.

💡 Hint

Calculate total data, then multiply by cache hit ratio.

Total data = 10 million * 500 KB = 5,000,000,000 KB = ~4.66 TB. 75% of this is served from cache edges, so ~3.5 TB. Rounded to 3.75 TB for simplicity.