CDN Modern Extensions & Advanced Use-Cases Quiz

Q1. In serverless edge computing, what does the term 'cold start' refer to? The practice of caching content on edge servers on the first request
The initial delay when an edge function is invoked and its runtime is not already warm
A technique for cooling down servers at edge data centers
The time it takes for DNS to propagate to edge locations

Q2. Which approach can help minimize cold start times for code running at the edge? Use lightweight isolate-based runtimes (e.g., V8 engine isolates) instead of heavy containerized VMs
Increase the size of the function's deployment package significantly
Choose a language runtime that has a longer startup time, like a Java VM
Add an artificial delay at the beginning of the function

Q3. In the context of edge storage, what is a key difference between a global key-value store and a Durable Object (as offered by Cloudflare)? Durable Objects are eventually consistent across regions, while the key-value store is strongly consistent
The key-value store is strongly consistent, replicating writes instantly worldwide
Durable Objects cannot retain any state between requests
A key-value store is eventually consistent globally, whereas a Durable Object provides strong consistency by routing all requests to a single instance

Q4. What is a common way to implement an A/B test for content while using a CDN's caching? Bypassing the CDN entirely so each variant is always fetched from origin
Using the client's IP address as the cache key for different variants
Assigning users a variant via a cookie or header and caching separate versions per that value
Letting the CDN randomly change the content for each user

Q5. Which streaming technology is best suited for real-time, sub-second latency video interactions (e.g., live video chat)? Apple HLS (HTTP Live Streaming)
MPEG-DASH
Progressive MP4 download
WebRTC

Q6. HLS and MPEG-DASH are similar because both: deliver video in small HTTP-based segments and adjust quality to the user's connection
use UDP instead of TCP to minimize stream latency
were developed by the same company
guarantee sub-second latency for live streams by default

Q7. What is a primary benefit of using modern image formats like AVIF or WebP on a website via CDN? They significantly degrade image quality to achieve smaller file sizes
They require users to install a special plugin or browser update to see the images
They drastically reduce image file sizes for comparable quality, resulting in faster loading times
They are mainly beneficial for video files rather than images

Q8. What is the purpose of the HTTP 103 Early Hints status code? To acknowledge a request and tell the client to continue sending it (like a '100 Continue')
To send the browser preliminary hints (e.g. preload links) while the server prepares the full response
To negotiate an upgrade to the HTTP/3 protocol
To indicate a temporary redirect that the client should follow

Q9. In a multi-CDN strategy, how is Real User Monitoring (RUM) data used? To distribute traffic evenly among CDNs in round-robin fashion
To allow each end user to manually choose which CDN to use
To dynamically route users to the CDN that currently offers the best performance for them
To always send traffic to one primary CDN unless it completely fails

Q10. Why might a company use a private or federated CDN with security zones? To restrict content delivery to authorized users or networks for security compliance
To intentionally slow down the delivery of its content
To allow anyone on the internet to access confidential assets
Because public CDNs cannot deliver video or dynamic content

Q11. How do technologies like eBPF and XDP improve performance in CDN edge servers? By compressing all images and videos on-the-fly at the edge
By allowing the server to filter or drop unwanted traffic in the kernel before it reaches the application
By offloading the CDN caching logic to the end user's browser
By adding additional network hops for processing

Q12. What is one benefit of using Kernel TLS (kTLS) on CDN servers? It lets the CDN operate without any SSL certificates
It sends data over the network unencrypted to reduce CPU usage
It offloads all encryption tasks to the client side
It performs TLS encryption in kernel space, reducing context switches and improving performance

Q13. Which of the following is true about AWS CloudFront Functions compared to Lambda@Edge? Lambda@Edge runs code inside the client's browser, whereas CloudFront Functions run on edge servers
CloudFront Functions are designed for short, fast execution and limited logic, whereas Lambda@Edge can run more complex code but with higher latency
CloudFront Functions support many programming languages, but Lambda@Edge only supports Node.js
Lambda@Edge is a newer service that has completely replaced CloudFront Functions

Q14. In a multi-CDN environment, what does 'SLA arbitration' typically involve? Mediating contract disputes between CDN providers
Using blockchain to automatically enforce CDN service agreements
Shifting user traffic to whichever CDN is meeting performance and uptime targets at a given time
Dividing traffic evenly across all CDNs regardless of performance

Q15. What does the HTTP 'Vary' header do in the context of CDN caching? Sets an IP address restriction on who can access the cached content
Makes the CDN serve a random variant of the content on each request
Forces the CDN to revalidate the cached content with the origin server on every request
Instructs caches to store separate versions of the response based on specified request headers (e.g., Cookie, User-Agent)

system-design