How to Prepare for a .NET Interview in Two Weeks

Two weeks is enough to walk into a mid-level .NET interview prepared — if you spend the time on the right things. Depth beats breadth: interviewers probe follow-ups, so a solid understanding of ten core topics is worth more than a shallow pass over fifty.

Week 1 — fundamentals you will be asked to explain

• Days 1–2: C# and the CLR. Value vs reference types, boxing, IEnumerable vs IQueryable, delegates and events, async/await (and the fact that awaiting I/O does not use a thread), and how the generational garbage collector decides what to collect.
• Days 3–4: ASP.NET Core. The middleware pipeline and its ordering rules, the built-in DI container, and the full lifetime story — Transient vs Scoped vs Singleton, why DbContext is scoped, and what a captive dependency is.
• Days 5–6: SQL Server. Clustered vs non-clustered indexes, key lookups, how to read an execution plan, INNER vs LEFT JOIN (and the WHERE-on-the-outer-table trap), and a repeatable method for tuning a slow query.
• Day 7: Entity Framework. Change tracking, AsNoTracking, lazy vs eager loading and the N+1 problem, and migrations.

Week 2 — practise out loud

• Days 8–10: mock answers. For each topic, say the answer aloud in two or three sentences, then be ready for the follow-up. Prismita's How to Answer in an Interview and Interviewer Follow-Ups sections are built for exactly this.
• Days 11–12: scenario questions. “An endpoint is slow under load”, “an intermittent NullReferenceException in production”, “users see stale data after a save.” Learn a structured way to reason, not a script.
• Day 13: your own projects. Be able to describe the architecture, one hard bug you fixed, and one decision you would make differently now.
• Day 14: light review. Re-read your weak-topic quick answers. Sleep.

What not to do

Do not try to memorise a hundred one-line answers. Interviewers can tell, and the first follow-up exposes it. Pick the core topics, understand the mechanism, and rehearse the thread.