Explanation:

In Microsoft 365 Defender's Advanced Hunting (Kusto Query Language - KQL) , investigators use the DeviceLogonEvents table to search for authentication attempts and filter failed logons. To detect failed sign- ins from specific devices, you begin by applying a where clause that filters only the relevant logon failures and the specific device names you want to investigate.
The correct syntax and logical order-based on Microsoft Security Operations (SecOps) and Microsoft 365 Defender hunting guide -is to first filter ( where ) the Ac tionType to "LogonFailed," then narrow down the dataset to the target devices ( DeviceName in ( " CFOLaptop " , " CEOLaptop " , " COOLaptop " ) ). This ensures that only failed authentication attempts from those three machines are included.
After filtering, the summarize operator is used to group the data by DeviceName and LogonType , counting how many failures occurred per device and logon type. This aggregation step follows Microsoft's recommended practice for incident hunting, allowing analysts to quickly assess which devices are generating unusual authentication failure volumes.
Finally, the project statement selects only the LogonFailures output, simplifying the results for reporting or alerting purposes.
This query structure aligns exactly with Microsoft 365 Defender Advanced Hunting documentation for detecting failed logins on specific endpoints while maintaining query efficiency and clarity, minimizing administrative overhead during investigations