API Gateway & Rate Limiting Flashcards
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Read the first 7 API Gateway & Rate Limiting flashcards as text
Which leaky bucket characteristic differentiates it from the token bucket algorithm?
Answer: Leaky bucket enforces a constant output rate; token bucket permits bursts up to capacity
The leaky bucket processes requests at a fixed constant rate regardless of input bursts, while the token bucket allows short bursts up to the bucket size.
An API gateway must route requests to different CDN origin clusters based on the API version in the URL path. What is this pattern called?
Answer: Path-based routing
Path-based routing directs traffic to different backends based on URL path segments, such as /v1/ or /v2/.
What does the Retry-After response header communicate to an API client after a 429 response?
Answer: How many seconds or a date until the client can retry
Retry-After tells the client either a delay in seconds or an HTTP-date after which it may safely retry the request.
Which security threat does an API gateway's rate limiter most directly mitigate against CDN infrastructure?
Answer: Credential stuffing and brute force attacks
Rate limiting restricts the number of login or token attempts, directly throttling credential stuffing and brute force attacks.
A CDN's API gateway implements mutual TLS (mTLS). What does the gateway verify in addition to the server certificate?
Answer: The client's certificate during the TLS handshake
In mTLS, both parties present certificates; the gateway verifies the client certificate to ensure only authorized clients connect.
What is the primary purpose of an API gateway's 'circuit breaker' pattern when integrated with a CDN?
Answer: To stop sending requests to a failing origin and return cached or error responses
A circuit breaker detects repeated failures to an origin and temporarily stops forwarding requests, protecting the origin from further overload.
Which HTTP method is typically exempt from CDN caching and therefore has the most direct impact on API gateway rate limiting?
Answer: POST
POST requests are not cached by CDNs because they carry request bodies and mutate state, so every POST hits the origin and the rate limiter.
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