CDN API Gateway & Rate Limiting 2

Question 1

Which rate limiting algorithm uses a continuously refilling virtual container to smooth out traffic bursts?

Accepted Answer

Token bucket

Answer

The token bucket algorithm refills tokens at a fixed rate and allows bursts up to the bucket capacity.

Question 2

An API gateway sitting in front of a CDN origin needs to enforce per-client quotas. Which HTTP header should the gateway return to tell clients when their quota resets?

Accepted Answer

X-RateLimit-Reset

Answer

X-RateLimit-Reset is the de facto standard header conveying the Unix timestamp when the rate limit window resets.

Question 3

A CDN's API gateway authenticates requests using JWT. Where should the gateway validate the JWT signature?

Accepted Answer

At the API gateway entry point before routing

Answer

JWT validation at the API gateway entry point ensures unauthenticated requests are rejected before consuming backend resources.

Question 4

Which strategy allows an API gateway to enforce rate limits consistently across multiple geographically distributed edge nodes?

Accepted Answer

Centralized distributed cache (e.g., Redis)

Answer

A centralized distributed cache like Redis lets all edge nodes share and atomically update the same rate limit counters.

Question 5

What HTTP status code should an API gateway return when a client exceeds its rate limit?

Accepted Answer

429 Too Many Requests

Answer

RFC 6585 defines 429 Too Many Requests as the correct response when a client has exceeded the allowed rate.

(CDN) Content Delivery Network Certification Practice Test

(CDN) Content Delivery Network Certification Practice Test

CDN API Gateway & Rate Limiting 2