N10-009 Question 20
Single answerApplications: Content delivery network (CDN)A company launches a new product and sees a sudden spike in traffic to its public website from users around the world. During the first hour, customers report slow page loads for images, style sheets, and video clips, even though the origin web server's CPU and memory are not fully utilized. The network administrator recommends adding a content delivery network (CDN). Which action would best address the performance issue?
- A
Deploy the static website content to CDN edge locations so users retrieve cached content from servers closer to their geographic region
- B
Replace the public DNS servers with an internal-only DNS solution so queries stay inside the corporate network
- C
Disable caching headers on static content so each user request is sent directly to the origin server for the latest version
- D
Move the website to a single higher-capacity server in the data center so all users connect to one more powerful host
Show answer and explanation
Correct answer: A
Explanation
A CDN is primarily used to improve the delivery of cacheable content by placing copies at distributed edge locations. For a global audience, this reduces round-trip time and helps offload the origin infrastructure. In real deployments, CDNs are commonly used for images, video segments, CSS, JavaScript, downloads, and other static assets. Best practices include using appropriate cache-control policies, keeping the origin available for cache misses, and leveraging DNS-based or anycast-based traffic steering depending on the provider. This aligns with common vendor documentation and web performance guidance from major CDN providers and HTTP caching standards such as those defined in RFC 9111.
- A. Correct.
Correct. A CDN improves performance by caching static or cacheable content at geographically distributed edge servers. This reduces latency for end users, lowers bandwidth demand on the origin, and helps absorb traffic spikes for objects such as images, CSS, JavaScript, and media files. In this scenario, globally distributed users are experiencing delays on static assets, which is exactly the kind of problem a CDN is designed to solve.
- B. Incorrect.
Incorrect. Internal-only DNS would make the public website less reachable, not more performant. CDNs commonly rely on public DNS resolution to direct users to appropriate edge locations. Replacing public DNS with internal-only DNS would not help external customers and misunderstands how public content delivery works.
- C. Incorrect.
Incorrect. Disabling caching headers would force more requests back to the origin server, increasing latency and bandwidth usage. This is the opposite of CDN best practice for static assets. Someone might choose this if they are focused only on content freshness, but for performance during a traffic spike, proper cache control is beneficial, not harmful.
- D. Incorrect.
Incorrect. A larger single server may improve origin capacity somewhat, but it does not solve the geographic latency problem for global users. It also creates continued dependence on one location for static content delivery. A CDN is more effective because it distributes content closer to users and reduces repeated origin fetches.