Overview

For an experienced .NET developer with roughly eight to nine years of experience, a strong interview should test judgment under trade-offs, not just recall. The candidate should be able to reason about service boundaries, modern supported .NET versions, asynchronous and concurrent programming, data-access behavior under load, API design, resilience, security, delivery, and team leadership. In May 2026, Microsoft’s supported modern .NET releases are .NET 8, .NET 9, and .NET 10, while .NET 6 has already reached end of support; that means interviews should usually treat .NET 6 as migration context, not as the preferred greenfield baseline. ASP.NET Core guidance also now explicitly positions Minimal APIs as the recommended starting point for new fast HTTP APIs, while the broader .NET microservices guidance continues to emphasize bounded contexts, inter-process communication, and cloud-native resilience patterns.

The most effective senior interview format is depth-first. In a 60-minute technical interview, you usually learn more from 12–16 well-chosen questions with layered follow-ups than from 30 shallow prompts. For this level, architecture judgment, advanced C# fluency, ASP.NET Core/Web API design, EF Core behavior, performance diagnosis, concurrency, and distributed-systems trade-offs should dominate. Security, testing, CI/CD, cloud basics, and behavioral leadership should still appear, but as higher-signal probes into operational maturity rather than checkbox topics. That weighting is consistent with current Microsoft guidance across ASP.NET Core APIs, EF Core performance, distributed application resilience, diagnostics, and testing.

The question bank below contains 50 interview questions. Each one includes a concise model answer, a deeper explanation, common pitfalls, and likely follow-ups. The intent is not that one interviewer asks all of them. The intent is to give you a rigorous bank that can be mixed by company style: product/backend platform teams will skew toward APIs, performance, and distributed systems; enterprise application teams will spend more time on ASP.NET Core, EF Core, testing, and modernization; platform teams will probe concurrency, diagnostics, CI/CD, and cloud deployment choices more aggressively.

Interview blueprint

The weighting below is a recommended structure for a 60-minute senior technical interview. It is a synthesis, not a Microsoft-prescribed rubric, but it is grounded in the current shape of the .NET ecosystem and the official guidance around APIs, diagnostics, resilience, data, testing, and cloud hosting.