Adjust Defender for Identity alert thresholds only after accounting for learning periods

Use this document to resolve one bounded operational decision: Adjust Defender for Identity alert thresholds only after accounting for learning periods. Only the official source and traced locations below supply facts. Confirm applicability before acting.

Source fact:

The official Adjust alert thresholds from Microsoft supports the following bounded statements:

• Some Defender for Identity alerts use learning periods to build activity profiles and distinguish legitimate from suspicious behavior. The research record locates this support at Threshold behavior explanation.
• The Adjust alert thresholds page changes alert volume, and Recommended test mode or Medium or Low settings can trigger alerts immediately even before a learning period completes. The research record locates this support at Threshold customization and trigger behavior.

These statements are the factual basis for this document. Do not extend them into a broader assurance. Review identity detections, contributing events, entities, alert logic, tuning, exclusions, investigation, and response decisions only where the source and recorded environment align.

What the source does not establish

Lowering or raising a threshold changes signal volume and can affect false positives or missed detections; document, test, and review every change. Do not read the source as proof of implementation or permission to change production. Its guidance remains conditional on Active Directory, Windows DNS, sensor health, time, network visibility, cloud analytics, endpoint evidence, and security operations and the environment’s recorded constraints.

Applicability questions

• For source statement 1 at Threshold behavior explanation, which observable configuration, record, or test can confirm applicability here?
• For source statement 2 at Threshold customization and trigger behavior, which observable configuration, record, or test can confirm applicability here?
• Which deployed instance of identity detections, contributing events, entities, alert logic, tuning, exclusions, investigation, and response decisions will be compared with the source, and why that instance?
• How will the review distinguish a source mismatch from a failure in Active Directory, Windows DNS, sensor health, time, network visibility, cloud analytics, endpoint evidence, and security operations?
• Who approves the conclusion, exception, test window, and rollback threshold?

DSE recommendation:

DSE recommends using the cited source as the evidence anchor for this decision. Start with applicability, then compare the observed state with the cited source. Record the source location, examined part of identity detections, contributing events, entities, alert logic, tuning, exclusions, investigation, and response decisions, observed and expected states, owner, and reason for deviation.

An implementation decision needs an owner, approved window, prechecks, observable outcome, stop authority, and rollback path. Validate Active Directory, Windows DNS, sensor health, time, network visibility, cloud analytics, endpoint evidence, and security operations before and after the test, and store only sanitized operational evidence.

Verification and evidence

Keep the source locations Threshold behavior explanation; Threshold customization and trigger behavior adjacent to the sanitized artifacts used for comparison. Prefer sanitized alerts, source events, entity timelines, tuning conditions, exclusion scope, analyst findings, and response outcomes, with enough identity and timing data for an independent recheck.

Keep before-state evidence, approval, test or change result, exceptions, and after-state evidence together. Use an approved lab, window, or nonproduction path for risky tests. Set a recheck trigger for version, architecture, dependency, vendor, incident, or ownership change. A check proves only what was observed.

Official references

• Adjust alert thresholds — Microsoft