What is Log Analytics?
Log Analytics is part of Azure Monitor that stores and queries log data.
Logs from different resources (VMs, apps, networking, security) are collected in a Log Analytics Workspace.
Think of it as a central log database where you can run queries, build reports, and detect issues.
Kusto Query Language (KQL)
KQL is the query language used to analyze logs in Azure.
-
Looks like SQL but is read-only (you can’t update data).
-
Designed for searching, filtering, and aggregating large sets of log data.
Basic Syntax Examples:
-
search "error"→ Finds all logs containing “error.” -
AzureActivity | where ResourceGroup == "TestRG"→ Filters logs by resource group. -
SecurityEvent | summarize count() by ResultType→ Groups by result type and counts events.
Common Data Sources for Logs
-
Activity Logs: Who did what at the subscription level.
-
Resource Logs: Events inside resources (e.g., SQL queries, firewall traffic).
-
VM Logs: Collected by agents (performance, syslogs, event viewer).
Confusion Buster 🚨
-
Metrics vs Logs
-
Metrics = performance numbers (fast, real-time).
-
Logs = events and activities (detailed, historical).
-
-
Activity Log vs Resource Log
-
Activity Log = subscription-level operations (create, delete resources).
-
Resource Log = inside the resource (queries, errors, requests).
-
Exam trap: If the question says “who deleted a VM?” → Activity Log. If it says “why is SQL DB slow?” → Resource Logs.
Simple Example
A company wants to monitor failed logins to their VM:
-
Logs are collected into Log Analytics Workspace.
-
Admin runs a KQL query:
SecurityEvent | where EventID == 4625 | summarize count() by Account -
This shows which accounts had failed login attempts.
Exam Tip
-
If you see “querying logs”, the answer involves Log Analytics Workspace + KQL.
-
If you see “real-time CPU/Memory usage”, that’s Metrics, not Logs.
-
If scenario asks “who deleted a resource?”, the answer is Activity Logs.
What to Expect in the Exam
-
Direct Q: “Which language is used to query logs in Azure?” → KQL.
-
Scenario: “Admin wants to analyze sign-in failures across multiple resources.” → Log Analytics + KQL.
-
Trick Q: “You can update resource logs with KQL queries.” (False — KQL is read-only).