What they’re likely testing C# OOP: classes vs. interfaces, immutability, async/await, LINQ, exceptions, dependency injection basics. .NET app patterns: web (ASP.NET/Razor/Blazor) and Windows services/Workers (lifetime, logging, retries, configuration). SQL Server: JOINs, GROUP BY/aggregations, indexing, query plans, transactions, isolation, parameterized queries. Testing: MSTest/xUnit, unit vs. integration tests, mocking, test data setup, edge cases. Coding portion (live or take-home–style, but timed) Expect 1–2 problems: arrays/maps/strings or a simple data-model + query. Emphasize clarity > cleverness. Narrate: “I’ll start with a correct O(n) solution, then we can consider memory trade-offs.” Rapid drill (practice these out loud) Implement Closest in sorted array (binary search variant) in C#. Write a method to dedupe patients by (first,last,DOB) using a Dictionary<(string,string,DateOnly), Patient>. Given tables Patients(id, last_seen) and Appointments(patient_id, date, status), write a query to list patients overdue > 12 months with no upcoming appointment. Explain index choice for Appointments(patient_id, date); what composite index and why. Sketch a Windows worker that runs an outreach job every hour with idempotency (e.g., job table with lock/lease).