Microservices Resilience and Fault Tolerance 5

Question 1

What is the primary risk of a 'retry storm' across many client instances?

Accepted Answer

Synchronized retries that suddenly multiply load and prolong or trigger an outage

Answer

Reduced log retention

Answer

Faster recovery of the downstream service

Answer

Lower memory usage on clients

Question 2

Which metric is most useful for tuning a circuit breaker's failure threshold?

Accepted Answer

The error or failure rate of calls within a rolling window

Answer

Lines of code

Answer

The number of git commits

Answer

The size of the Docker image

Question 3

What is the benefit of caching responses as a fallback during a downstream outage?

Accepted Answer

It allows serving slightly stale but usable data instead of an error

Answer

It guarantees data is always real-time

Answer

It removes the need for a database

Answer

It encrypts the downstream call

Question 4

In distributed systems, why does the timeout budget need to be coordinated across a call chain?

Accepted Answer

So an upstream timeout isn't shorter than the sum of downstream timeouts, causing wasted work

Answer

To make all services use the same language

Answer

To reduce the number of microservices

Answer

To synchronize clocks

Question 5

What does the term 'blast radius' mean in resilience design?

Accepted Answer

The scope of impact a single failure can have on the rest of the system

Answer

The geographic spread of data centers

Answer

The number of API endpoints

Answer

The maximum payload size

Question 6

Why is observability (metrics, logs, traces) critical to fault tolerance?

Accepted Answer

It enables fast detection and diagnosis of failures so the system can react and recover

Answer

It replaces the need for retries

Answer

It encrypts all traffic

Answer

It eliminates the need for circuit breakers

Question 7

What is a key advantage of deploying redundant service instances across availability zones?

Accepted Answer

It tolerates a zone-level outage by keeping instances running elsewhere

Answer

It reduces total infrastructure cost to zero

Answer

It removes the need for load balancing

Answer

It guarantees zero latency