CDN Cost Optimization & Traffic Management 3 — Questions and Answers
Question 1: What CDN cost optimization technique involves compressing text-based responses before delivering them to end users?
- Minification only
- Gzip or Brotli compression (Correct answer)
- Image transcoding
- Protocol downgrading
Correct answer: Gzip or Brotli compression
Gzip and Brotli compression reduce the byte size of text responses, directly lowering egress data transfer costs.
Question 2: A media company streams live events globally. Which CDN traffic management strategy best handles sudden audience spikes?
- Single-origin pull with no caching
- Multi-CDN failover with auto-scaling (Correct answer)
- Static IP-based routing
- Manual capacity reservation per region
Correct answer: Multi-CDN failover with auto-scaling
Multi-CDN failover with auto-scaling distributes load across providers and dynamically adjusts capacity, preventing bottlenecks during live event spikes.
Question 3: Which HTTP header instructs a CDN to NOT cache a response and always fetch fresh content from origin?
- Cache-Control: max-age=3600
- Cache-Control: no-store (Correct answer)
- Vary: Accept-Encoding
- ETag: abc123
Correct answer: Cache-Control: no-store
Cache-Control: no-store tells both CDN edge nodes and browsers not to store any version of the response, forcing every request to the origin.
Question 4: A global e-commerce site wants to reduce CDN costs for product images. Which combination of techniques provides the greatest savings?
- Increase image resolution and disable compression
- Convert images to WebP format and set long cache TTLs (Correct answer)
- Serve all images from a single origin region
- Use HTTP/1.1 instead of HTTP/2
Correct answer: Convert images to WebP format and set long cache TTLs
WebP provides superior compression ratios versus JPEG/PNG, and long TTLs maximize cache hit rates, both reducing bytes transferred and origin requests.
Question 5: What is the primary purpose of CDN traffic shaping in a cost optimization context?
- To increase the number of CDN PoPs
- To prioritize or throttle specific traffic types to control bandwidth costs (Correct answer)
- To encrypt all traffic between users and edge nodes
- To replace origin servers entirely
Correct answer: To prioritize or throttle specific traffic types to control bandwidth costs
Traffic shaping lets CDN operators throttle lower-priority traffic and reserve bandwidth for high-value content, preventing unexpected egress cost overruns.
Question 6: A SaaS company notices that 40% of their CDN requests return a 404 status for non-existent resources. How does this affect costs?
- No cost impact since 404s are cached at the edge
- It increases costs because 404 responses are typically not cached and hit the origin (Correct answer)
- It reduces costs because 404 responses are smaller in size
- It has no impact since CDNs don't bill for error responses
Correct answer: It increases costs because 404 responses are typically not cached and hit the origin
Non-cacheable 404 responses cause repeated origin fetches, generating both unnecessary egress charges and origin compute costs.
Question 7: Which CDN feature enables serving different content variants (e.g., mobile vs. desktop) from cache without separate origin requests for each?
- Vary header-based caching (Correct answer)
- Edge-side includes (ESI)
- Prefetch directives
- WebSocket tunneling
Correct answer: Vary header-based caching
The Vary header instructs the CDN to cache separate versions of a response per header value (e.g., User-Agent), serving the correct variant from cache.
CDN Cost Optimization & Traffic Management 3
What CDN cost optimization technique involves compressing text-based responses before delivering them to end users?