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Free OTCA practice test: 30 questions with answers

30 original questions for OpenTelemetry Certified Associate, drawn from every topic area. Answer each one to see whether you got it right and why. No sign-up.

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All 30 OTCA questions with answers

The same questions as the test above, grouped by exam topic. Open any question to see the answer and explanation.

Observability Concepts and Signals (8 questions)

  1. Question 1

    Which OpenTelemetry signal records the path of a single request as it moves across multiple services, including timing for each operation?

    1. ALogs only
    2. BProfiles of disk usage
    3. CMetrics
    4. DTraces
    Show answer and explanation
    Correct answer: D

    Traces capture a request's journey as spans with timing and parent-child relationships. Metrics aggregate numeric measurements, logs record events, and disk profiles are not a core signal.

  2. Question 2

    Which signal is best suited to tracking the total number of HTTP requests per second over time with low storage cost?

    1. AMetrics
    2. BTraces for every request
    3. CUnstructured log lines only
    4. DScreenshots of dashboards
    Show answer and explanation
    Correct answer: A

    Metrics are aggregated numeric time series that are efficient for rates and counts over time. Tracing every request is expensive for this purpose, and log lines and screenshots are not efficient for rate tracking.

  3. Question 3

    What is a span in OpenTelemetry?

    1. AA timed operation within a trace that has a name, start and end times, and attributes
    2. BA permanent row in a relational database table, with a primary key assigned by the storage engine
    3. CA unit of CPU time on a compute node, measured in cycles and summed per process by the kernel
    4. DA dashboard panel that plots a time series chart with a query, legend, and visualization type
    Show answer and explanation
    Correct answer: A

    A span is a timed unit of work within a trace, with attributes and relationships to other spans. CPU units, database records and dashboard panels are unrelated.

  4. Question 4

    Spans within one trace are linked so that a child operation references its parent. What identifies the trace across services?

    1. AThe trace ID propagated in request context
    2. BThe dashboard title set in Grafana for the panel
    3. CThe host's IP address alone, logged per service
    4. DThe log file name written by the logging agent
    Show answer and explanation
    Correct answer: A

    The trace ID is propagated through context so every service can attach its spans to the same trace. IP addresses, file names and dashboard titles do not connect spans across services.

  5. Question 5

    Which concept describes the information that identifies the source of telemetry, such as the service name and host, attached to all signals?

    1. AHistogram buckets
    2. BSampling probability
    3. CSpan events only
    4. DResource attributes
    Show answer and explanation
    Correct answer: D

    Resource attributes describe the entity producing telemetry, such as service name and host. Span events, histogram buckets and sampling probabilities describe other aspects.

  6. Question 6

    Which OpenTelemetry metric instrument is most appropriate for a value that can increase and decrease, such as the number of active connections?

    1. ACounter that only increases
    2. BLog record
    3. CHistogram of request durations
    4. DUpDownCounter
    Show answer and explanation
    Correct answer: D

    An UpDownCounter tracks values that can rise and fall, such as active connections. A Counter only increases, a histogram records distributions, and log records are not metric instruments.

  7. Question 7

    A team wants to see the distribution of request latencies, including percentiles, not only the average. Which metric instrument should be used?

    1. AGauge that stores the last value only
    2. BCounter for total requests only
    3. CHistogram
    4. DLog line for every request
    Show answer and explanation
    Correct answer: C

    A histogram captures the distribution of measurements, which enables percentile analysis. A last-value gauge, a total counter and log lines do not describe distributions.

  8. Question 8

    Which signal is best for detailed, structured event records that include context such as an error message and the request that caused it?

    1. ASampling rules
    2. BResource detection
    3. CLogs
    4. DMetrics only
    Show answer and explanation
    Correct answer: C

    Logs capture structured event records with context. Metrics aggregate values, sampling rules control trace collection, and resource detection identifies the source.

OpenTelemetry Collector (8 questions)

  1. Question 9

    In the OpenTelemetry Collector, what is a receiver?

    1. AA component that sends telemetry to a backend over OTLP
    2. BA dashboard panel that renders time series charts from stored metrics for operators
    3. CA component that accepts telemetry data from applications or other sources
    4. DA database index structure, such as a B-tree on a timestamp column, used for lookups
    Show answer and explanation
    Correct answer: C

    Receivers accept telemetry into the Collector. Exporters send telemetry out, dashboards display data and indexes are database structures.

  2. Question 10

    In the Collector, what is the role of an exporter?

    1. ASending telemetry to a backend or another system
    2. BDrawing time series charts and heatmaps for on-call staff
    3. CReceiving telemetry from applications directly
    4. DCreating spans in the application code using the SDK
    Show answer and explanation
    Correct answer: A

    Exporters send processed telemetry to backends or other systems. Receivers accept data, instrumentation creates spans, and charts are backend features.

  3. Question 11

    What does a processor do in a Collector pipeline?

    1. ARenders dashboards and visualizations for end users in Grafana
    2. BTransforms, filters, batches, or enriches telemetry between receivers and exporters
    3. CAccepts incoming HTTP requests from end users on port 4318 before login checks
    4. DStores telemetry permanently in the Collector's memory for long-term retention
    Show answer and explanation
    Correct answer: B

    Processors modify telemetry between receiving and exporting, such as batching or filtering. Accepting user requests, storing permanently in memory and rendering dashboards are not processor roles.

  4. Question 12

    Which two components are part of a Collector pipeline? (Choose two.)

    1. AReceivers
    2. BExporters
    3. CDashboards inside the Collector
    4. DDatabase indexes
    5. EPrinter drivers
    Show answer and explanation
    Correct answer: A, B

    Receivers and exporters are pipeline components, with processors between them. Dashboards, indexes and printer drivers are not Collector components.

  5. Question 13

    A Collector receives OTLP data over gRPC and HTTP. Which configuration describes both protocols?

    1. AAn OTLP receiver with both the gRPC and HTTP endpoints configured
    2. BA dashboard with two tabs, one for gRPC traffic and one for HTTP traffic
    3. CA single exporter with two passwords and two separate authentication tokens
    4. DA processor that accepts HTTP requests and forwards them to the exporter queue
    Show answer and explanation
    Correct answer: A

    The OTLP receiver can expose gRPC and HTTP endpoints, which is how Collectors accept both. Exporters, processors and dashboards do not accept protocol requests.

  6. Question 14

    Which Collector component should be used to add the Kubernetes pod name to every span without changing the application?

    1. AAn exporter that deletes spans older than the retention window from memory
    2. BA processor that enriches telemetry with resource detection or Kubernetes metadata
    3. CA receiver that drops resource attributes from incoming payloads
    4. DA dashboard setting for the default time range and panel refresh
    Show answer and explanation
    Correct answer: B

    Enrichment processors and detectors add Kubernetes metadata to telemetry without application changes. Exporters, receivers that drop attributes and dashboards do not add this context.

  7. Question 15

    A team wants to route traces to one backend and metrics to another. Which Collector design supports this?

    1. ASeparate pipelines for traces and metrics, each with its own exporter
    2. BTurning off one signal entirely
    3. CA single pipeline that sends everything to both backends regardless of type
    4. DStoring traces in a text file on the Collector host
    Show answer and explanation
    Correct answer: A

    Separate signal pipelines with their own exporters route each signal to the right backend. Sending everything to both, disabling a signal and file storage do not meet the routing requirement.

  8. Question 16

    Which Collector configuration section defines the connections between receivers, processors, and exporters for each signal?

    1. Athe extensions block only
    2. Ba comment at the top of the file
    3. Cservice pipelines
    4. Dthe exporters block only
    Show answer and explanation
    Correct answer: C

    The service section defines pipelines that connect components for each signal. Exporter definitions alone do not connect the pipeline, extensions serve auxiliary functions, and comments have no effect.

Instrumentation (7 questions)

  1. Question 17

    Which instrumentation approach adds telemetry to an application without changing its source code?

    1. AAutomatic instrumentation using an agent or library hooks
    2. BPrinting variable values to the console output with print calls
    3. CManual instrumentation written into every function in the codebase
    4. DEditing the database schema and column types
    Show answer and explanation
    Correct answer: A

    Automatic instrumentation attaches to libraries or runtimes without code changes. Manual instrumentation requires code edits, console prints are not instrumentation, and schema edits are unrelated.

  2. Question 18

    A team needs custom spans around a business operation that is not covered by automatic instrumentation. Which approach fits?

    1. ALogging the operation only once per day as a summary entry written to the rotated application log file
    2. BManual instrumentation using the OpenTelemetry API to create spans around that operation
    3. CTurning off telemetry collection in the SDK for the whole service process
    4. DWaiting for the vendor to add support for custom spans in a future release of the commercial SDK
    Show answer and explanation
    Correct answer: B

    Manual instrumentation with the API creates spans for custom operations. Disabling telemetry, daily logs and waiting for support do not provide the spans.

  3. Question 19

    Which component provides the APIs that application code calls to create telemetry, separate from the implementation that exports it?

    1. AThe Collector's exporter only
    2. BThe database driver
    3. CThe OpenTelemetry API
    4. DThe Kubernetes scheduler
    Show answer and explanation
    Correct answer: C

    The API defines how code creates telemetry, while the SDK implements processing and export. The Collector receives and forwards telemetry, and the scheduler and database driver are unrelated.

  4. Question 20

    Which component implements the behavior behind the OpenTelemetry API, including sampling, batching, and exporting telemetry?

    1. AThe OpenTelemetry SDK
    2. BThe browser's developer tools
    3. CA printer driver
    4. DThe DNS resolver
    Show answer and explanation
    Correct answer: A

    The SDK implements processing, sampling, batching and export. Browser tools, printer drivers and DNS resolvers are unrelated.

  5. Question 21

    A service must pass the trace context to a downstream HTTP call so that the downstream spans join the same trace. Which standard header is used by default?

    1. AX-Random-ID
    2. BContent-Length
    3. CAccept-Encoding
    4. Dtraceparent
    Show answer and explanation
    Correct answer: D

    The W3C traceparent header carries trace context between services. The other headers do not carry trace identity.

  6. Question 22

    Context propagation is broken and each service shows a separate trace. What is the most likely cause?

    1. AThe service runs too many replicas behind a load balancer with sticky sessions disabled
    2. BTrace context is not extracted or injected at a service boundary, such as a message queue or HTTP client
    3. CThe service name is too long and exceeds the 63-character limit for names that the backend indexes
    4. DThe metrics dashboard is not refreshed often enough, so panels show stale values
    Show answer and explanation
    Correct answer: B

    Missing context injection or extraction at boundaries separates traces. Name lengths, replica counts and dashboard refreshes do not break trace linkage.

  7. Question 23

    Which attribute type is used to attach contextual details such as a customer tier to a span?

    1. AHistogram bucket boundary
    2. BSampling decision flag
    3. CSpan attribute
    4. DResource detector plugin only
    Show answer and explanation
    Correct answer: C

    Span attributes attach contextual key-value details to spans. Histogram boundaries, detector plugins and sampling flags serve other purposes.

Sampling and Performance (7 questions)

  1. Question 24

    A service needs its traces sampled at a fixed ratio, while still propagating the trace context to downstream services so they can make their own decisions. Which behavior is correct?

    1. APropagating the sampling decision in the trace context so downstream services respect it
    2. BIgnoring the sampling decision so each downstream service samples independently of the parent span
    3. CDropping the trace context header at the service boundary before the outbound call
    4. DDeferring sampling to the database layer after spans have been stored
    Show answer and explanation
    Correct answer: A

    Propagating the sampling decision keeps traces consistent across services. Ignoring decisions creates partial traces, dropping context breaks linkage, and database-only sampling does not apply to the whole trace.

  2. Question 25

    A team wants to measure how many spans are dropped by the Collector due to memory limits. Which signal helps detect this?

    1. AThe application's source code comments and inline docstrings
    2. BThe backend's dashboard color theme and default panel layout
    3. CThe number of production deployments per week for each team
    4. DCollector internal metrics for refused or dropped data
    Show answer and explanation
    Correct answer: D

    Collector internal metrics report refused and dropped telemetry. Source comments, themes and deployment counts do not measure drops.

  3. Question 26

    Which metric name convention helps monitoring teams find related instruments quickly?

    1. AUsing a consistent namespace prefix and descriptive names with units
    2. BChanging metric names with every version release to match the new build numbering
    3. CUsing random alphanumeric characters in metric names
    4. DNaming metrics after the office location and floor number
    Show answer and explanation
    Correct answer: A

    Consistent prefixes and descriptive names with units help discovery and reuse. Random, location-based and frequently changed names reduce clarity.

  4. Question 27

    Which two practices help keep trace data cost-effective? (Choose two.)

    1. ALimiting attribute values with high cardinality
    2. BRecording full request payloads on every span
    3. CKeeping every span forever
    4. DDuplicating spans in several pipelines
    5. ESampling traces appropriately
    Show answer and explanation
    Correct answer: A, E

    Sampling and limiting high-cardinality values control volume and cost. Full payloads, indefinite retention and duplication all raise cost.

  5. Question 28

    A team wants to reduce cost by sampling only traces of successful requests while keeping all errors. Which sampling approach is most appropriate?

    1. ATail sampling with a policy that keeps errors and samples successful traces at a lower rate
    2. BHead sampling at a fixed 1 percent rate with no error-based policy configured
    3. CDropping every trace from the store once it is more than one hour old, regardless of its status code
    4. DKeeping every trace in full without applying a sampling policy anywhere
    Show answer and explanation
    Correct answer: A

    Tail sampling can keep all errors and sample successful traces, meeting both goals. Head sampling without error policy can drop errors, daily dropping loses data, and no sampling ignores cost.

  6. Question 29

    A high-volume service emits many similar logs per second. Which practice reduces volume while keeping useful information?

    1. APrinting every log line to the console in the production environment
    2. BWriting logs to disk just once per calendar year to conserve space
    3. CSampling or aggregating repetitive logs and keeping error-level logs unsampled
    4. DDropping warnings and errors from the pipeline during peak traffic hours
    Show answer and explanation
    Correct answer: C

    Sampling repetitive logs and keeping errors unsampled reduces volume while preserving important information. Console printing, yearly writes and dropping errors remove needed data.

  7. Question 30

    A team sees that metric cardinality is growing after a code change added a new attribute. What should they do first?

    1. ADeleting the monitoring system and its alerting and paging rules
    2. BIgnoring cardinality because a metric is a cheap aggregate that carries no per-request storage cost
    3. CAdding more storage to the metrics backend without reviewing the cardinality of the new label
    4. DReviewing the attribute and removing it from metrics if it has unbounded values
    Show answer and explanation
    Correct answer: D

    Removing unbounded attributes from metrics addresses the root cause. Adding storage, deleting monitoring and ignoring cardinality do not solve the problem.