Microservices Monitoring, Logging, and Tracing 3

Question 1

What problem does sampling solve in distributed tracing?

Accepted Answer

Reducing the volume and cost of stored traces while keeping representative data

Answer

Sampling keeps a subset of traces to control storage and processing costs while preserving useful signal.

Question 2

Which of these are the three pillars of observability?

Accepted Answer

Metrics, logs, and traces

Answer

Observability is commonly described through metrics, logs, and traces working together.

Question 3

What does a Service Level Indicator (SLI) measure?

Accepted Answer

A quantitative measure of a service's performance, like latency or error rate

Answer

An SLI is a measured metric reflecting service quality, such as request latency or availability.

Question 4

In tail-based sampling, when is the sampling decision made?

Accepted Answer

After the full trace completes, allowing decisions based on errors or latency

Answer

Tail-based sampling waits until the trace finishes so it can prioritize slow or errored traces.

Question 5

Why is high-cardinality data a concern in metrics systems like Prometheus?

Accepted Answer

Many unique label combinations explode time-series count and memory usage

Answer

Each unique label combination creates a separate time series, so high cardinality can overwhelm storage and memory.

Microservices Practice Test