CDN concept and usage in HLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

How does a CDN improve website load times?

Imagine you have a website hosted in one country, but visitors come from all over the world. How does a CDN help make the website load faster for these visitors?

A By blocking visitors from faraway locations to reduce server load.

B By compressing the website content only at the origin server before sending it to visitors.

C By increasing the bandwidth of the origin server to handle more visitors at once.

D By storing copies of website content in servers closer to visitors, reducing the distance data travels.

💡 Hint

Think about how distance affects delivery speed of packages in real life.

A CDN stores copies of content in many locations worldwide. This means visitors get data from a nearby server, making loading faster. Other options do not reduce distance or improve delivery speed globally.

❓ Architecture

intermediate

Which component is NOT part of a typical CDN architecture?

Consider the main parts of a CDN system. Which of these is usually NOT included in the CDN architecture?

A User devices that store permanent copies of website data.

B Edge servers that cache content close to users.

C Load balancers to distribute traffic among edge servers.

D Origin servers where the original content is stored.

💡 Hint

Think about which components the CDN controls versus user devices.

CDNs include edge servers, origin servers, and load balancers to manage traffic and caching. User devices are outside the CDN architecture and do not store permanent website copies as part of the CDN.

❓ scaling

advanced

How does a CDN handle sudden traffic spikes to a website?

A popular website suddenly gets a huge number of visitors. How does the CDN help the website handle this spike without crashing?

A By sending all traffic directly to the origin server to keep edge servers free.

B By shutting down some edge servers to reduce the number of requests processed.

C By distributing the traffic load across many edge servers worldwide, preventing overload on the origin server.

D By limiting the number of visitors allowed to access the website at once.

💡 Hint

Think about how spreading work among many helpers can prevent one from getting overwhelmed.

CDNs spread incoming requests across many edge servers, so no single server or the origin is overwhelmed. This helps the website stay available during traffic spikes. Other options reduce availability or increase load on origin.

❓ tradeoff

advanced

What is a tradeoff when using a CDN for dynamic content?

CDNs work well for static content like images. What is a common tradeoff when using a CDN to deliver dynamic content that changes often?

A Dynamic content may be delayed or outdated because caching can cause stale data to be served.

B Using a CDN for dynamic content eliminates the need for an origin server.

C Dynamic content is always faster because CDNs do not cache it at all.

D Dynamic content cannot be encrypted when delivered through a CDN.

💡 Hint

Think about how caching works and what happens if content changes frequently.

CDNs cache content to speed delivery. For dynamic content that changes often, caching can cause users to see old data until the cache updates. Other options are incorrect because CDNs can cache dynamic content with care, origin servers are still needed, and encryption is supported.

❓ estimation

expert

Estimate bandwidth savings using a CDN for a global website

A website serves 1 TB of data monthly from its origin server without a CDN. After adding a CDN, 80% of requests are served from edge caches. How much bandwidth does the origin server save monthly?

A 1 TB saved, because the CDN handles all traffic now.

B 0.8 TB saved, because 80% of data is served from the CDN edges.

C 0.2 TB saved, because only 20% of data is served from the CDN edges.

D No bandwidth saved, because the origin still sends all data.

💡 Hint

Calculate the percentage of data served by the CDN edges versus the origin.

If 80% of requests are served by CDN edges, the origin only sends 20% of data. So the origin saves 80% of bandwidth, which is 0.8 TB out of 1 TB.