Agent Configuration, Dynamic Focus Queries, and Sensor Management
This domain tests agent configuration files and environment variables, Dynamic Focus Query syntax, and sensor lifecycle management. Questions often ask how to scope a query, disable a noisy sensor, or avoid conflicting configuration.
Configuration layers
Agent settings include key, endpoint, zone, tags, proxy, and per-sensor blocks. Host agents read configuration.yaml; container and Kubernetes deployments commonly inject environment variables and Secrets. Treat the agent key as a secret. Keep one source of truth and confirm precedence for your deployment method.
Dynamic Focus Queries
DFQs filter entities in dashboards, alerts, and application views. Use fields such as entity.type, entity.label, entity.zone, and entity.tag, with AND, OR, NOT, wildcards, and parentheses. Quote values containing spaces or special characters. Start broad, test the query in the UI, then narrow it.
Sensor management
Sensors are plugins that collect technology-specific data. They are usually auto-discovered. Disable a sensor with a com.instana.plugin.<sensor> block using enabled: false, or manage it through the sensor management interface. Record why a sensor is disabled so future owners do not troubleshoot a deliberate gap.
Worked example
Scope an alert to production hosts but exclude canaries: entity.type:host AND entity.zone:prod AND NOT entity.label:*canary*. Test that zone values exactly match host tags; if no entities return, remove clauses one at a time.
Traps
Mixing entity types in one DFQ, assuming case-insensitive values, and disabling a sensor globally when only one host is noisy are common errors.