Monitoring, Alerting & Troubleshooting Flashcards
7 cards from real PCA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Monitoring, Alerting & Troubleshooting flashcards as text
What is the role of the Prometheus Pushgateway?
Answer: Allow short-lived batch jobs to expose metrics to Prometheus
Pushgateway acts as an intermediary so ephemeral jobs that cannot be scraped directly can push their metrics before they exit.
When using `topk(3, metric)` in PromQL, what does the result contain?
Answer: The three time series with the highest current values
topk(n, v) returns the n time series with the highest instantaneous values at the current evaluation timestamp.
A Prometheus server shows high memory usage. Which configuration change is most likely to reduce memory consumption?
Answer: Increase scrape_interval to reduce ingestion rate
Increasing the scrape interval reduces the volume of samples ingested per unit time, which directly lowers memory usage for the TSDB head block.
What does `vector(0)` return in PromQL?
Answer: A vector containing a single element with value 0 and no labels
vector(scalar) converts a scalar value into an instant vector with a single element, which is useful for arithmetic comparisons.
In Alertmanager, what is the difference between `resolve_timeout` and the `for` clause in a Prometheus alerting rule?
Answer: for controls when an alert fires; resolve_timeout controls how long Alertmanager waits before marking it resolved
The for clause in Prometheus determines how long a condition must be true before alerting, while resolve_timeout in Alertmanager sets how long to wait after the condition clears before sending a resolution notification.
Which PromQL operator would you use to keep only time series whose label value matches a regular expression?
Answer: {label=~"regex"}
The =~ operator in label matchers selects time series where the label value matches the provided regular expression.
What is the significance of the `__name__` label in Prometheus?
Answer: It holds the metric name and can be used in label matchers
__name__ is the internal label that stores the metric name, and it can be used in label matchers or relabeling rules to reference or rename metrics.