CDN Cost Optimization & Traffic Management 5 — Questions and Answers
Question 1: A multi-CDN architecture routes traffic based on real-time performance scores. What is the PRIMARY cost trade-off of this approach?
- Lower latency always reduces CDN unit costs
- Routing intelligence overhead adds operational complexity but can reduce overall spend by avoiding SLA penalties (Correct answer)
- Multi-CDN always costs more than single-CDN without performance benefits
- Performance-based routing eliminates the need for origin servers
Correct answer: Routing intelligence overhead adds operational complexity but can reduce overall spend by avoiding SLA penalties
Multi-CDN routing adds orchestration complexity and tooling costs but can reduce spend by leveraging competitive pricing and avoiding costly SLA breach penalties.
Question 2: Which mechanism allows a CDN to serve content from a nearby PoP even when the authoritative PoP for that region is overloaded?
- Anycast failover to an alternate PoP (Correct answer)
- Increasing origin server capacity
- Reducing DNS TTL to zero
- Disabling SSL termination at the edge
Correct answer: Anycast failover to an alternate PoP
Anycast routing automatically redirects traffic to the next-best available PoP when the primary PoP is overloaded, maintaining availability without manual intervention.
Question 3: A CDN customer wants to reduce costs for an API that serves personalized responses. What caching strategy is appropriate?
- Cache all API responses with a 24-hour TTL
- Use edge-side includes to cache the non-personalized skeleton and fetch only personalized fragments from origin (Correct answer)
- Disable the CDN for all API traffic
- Cache responses keyed by full URL including all query parameters
Correct answer: Use edge-side includes to cache the non-personalized skeleton and fetch only personalized fragments from origin
ESI allows the CDN to cache the static portions of a page/response while only fetching dynamic, personalized fragments from origin, balancing cost and personalization.
Question 4: What is 'egress cost optimization through protocol efficiency' in a CDN context?
- Switching from HTTPS to HTTP to save encryption overhead
- Using HTTP/2 or HTTP/3 multiplexing to serve more content per connection, reducing connection overhead costs (Correct answer)
- Increasing TCP window sizes to send more data per packet
- Disabling compression to reduce CPU costs at edge nodes
Correct answer: Using HTTP/2 or HTTP/3 multiplexing to serve more content per connection, reducing connection overhead costs
HTTP/2 and HTTP/3 multiplex multiple requests over a single connection, reducing connection establishment overhead and improving throughput efficiency.
Question 5: A CDN provider offers 'commit discounts' of 20% for 50 TB/month commitments. A customer averages 45 TB/month with peaks of 70 TB. What is the optimal procurement strategy?
- Commit to 70 TB to guarantee peak coverage at the discounted rate
- Commit to 50 TB for the discount and pay on-demand rates for overage above 50 TB (Correct answer)
- Use only pay-as-you-go to avoid over-commitment risk
- Commit to 45 TB matching the average usage
Correct answer: Commit to 50 TB for the discount and pay on-demand rates for overage above 50 TB
Committing at 50 TB captures the discount for most monthly usage while limiting over-commitment exposure; peak overage is handled at on-demand rates.
Question 6: Which CDN traffic management feature automatically routes traffic away from a failing origin region to a healthy backup region?
- Rate limiting
- Automatic failover / origin health checks (Correct answer)
- Request collapsing
- Cache purging
Correct answer: Automatic failover / origin health checks
Origin health checks continuously probe origin endpoints and trigger automatic failover to backup origins when primary origins become unresponsive.
Question 7: A CDN customer is evaluating costs for a static website with highly cacheable assets. Which metric should they prioritize to minimize monthly bills?
- Number of CDN PoPs in contract
- Cache hit ratio (origin offload rate) (Correct answer)
- SSL certificate renewal frequency
- DNS query volume
Correct answer: Cache hit ratio (origin offload rate)
For highly cacheable static content, maximizing the cache hit ratio directly minimizes origin egress charges and is the most cost-sensitive metric to track.
CDN Cost Optimization & Traffic Management 5
A multi-CDN architecture routes traffic based on real-time performance scores.
What is the PRIMARY cost trade-off of this approach?