CDN caching rules in Azure - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

How does CDN caching improve website performance?

Imagine you have a website with visitors all over the world. How does using a CDN caching rule help improve the speed of your website?

A By storing copies of website content closer to users, reducing load times.

B By increasing the size of the website files to make them load slower.

C By forcing all users to access the original server directly every time.

D By disabling all caching to ensure fresh content always loads.

💡 Hint

Think about how distance affects how fast data travels on the internet.

CDNs cache content near users, so data travels a shorter distance, making websites load faster.

❓ Architecture

intermediate

Which Azure CDN caching rule setup best handles frequently updated images?

You have images on your website that update every hour. Which caching rule setup ensures users see fresh images but still benefits from caching?

A Disable caching for images completely.

B Set cache duration to 24 hours with no revalidation.

C Set cache duration to 1 hour and enable cache revalidation.

D Set cache duration to 1 week to reduce server load.

💡 Hint

Consider how often the images change and how caching duration affects freshness.

Setting cache duration to 1 hour matches the update frequency, and revalidation ensures freshness.

❓ scaling

advanced

How does Azure CDN caching rules affect scalability during traffic spikes?

Your website experiences sudden traffic spikes. How do CDN caching rules help maintain performance and scalability?

A By serving cached content from edge locations, reducing origin server load.

B By sending all requests to the origin server to ensure fresh data.

C By disabling caching to force real-time data delivery.

D By limiting the number of users who can access the site simultaneously.

💡 Hint

Think about how caching reduces work for the main server during high demand.

Cached content served from CDN edges reduces origin server load, helping handle more users smoothly.

❓ tradeoff

advanced

What is a tradeoff when setting very long cache durations in Azure CDN caching rules?

Choosing a very long cache duration can improve performance but may cause what issue?

A The origin server will receive more requests.

B Users may see outdated content until cache expires.

C The CDN will use more bandwidth than usual.

D Cache will refresh too frequently, increasing latency.

💡 Hint

Think about how caching duration affects content freshness.

Long cache durations mean content stays cached longer, so updates may not appear immediately to users.

❓ estimation

expert

Estimate the cache hit ratio impact when enabling Azure CDN caching for static assets

Your website serves 1 million requests per day. 70% are for static assets like images and scripts. If Azure CDN caching is enabled with proper rules, what is the expected cache hit ratio and how many requests will reach the origin server?

A Cache hit ratio ~30%, so about 700,000 requests reach origin.

B Cache hit ratio ~50%, so about 500,000 requests reach origin.

C Cache hit ratio ~95%, so about 50,000 requests reach origin.

D Cache hit ratio ~85%, so about 150,000 requests reach origin.

💡 Hint

Consider that static assets are highly cacheable and most requests for them will be served by CDN.

With 70% static requests and good caching, about 85% of total requests hit cache, leaving 15% (150,000) to origin.