2026 .NET interview guide

2026 guide to .NET interviews
18 minutes by Mukesh Murugan

Modern .NET interviews focus on real scenarios, not definitions. Questions like "you injected a scoped service into a singleton and data is corrupting in production, why?" reveal far more than asking someone to define dependency injection. Strong candidates reason through trade-offs, state a clear default, and explain when they would deviate. Weak ones recite textbook answers, say "it depends" without follow-up, or stay stuck on outdated patterns.

Your Agent Needs Its Own Computer
sponsored by LangChain

Agents can write and run code seconds before execution, often without human review.  Local environments and standard containers weren’t designed for that level of autonomy. LangChain’s latest guide explains what safe agent execution requires, including isolation, permissions, observability, fast provisioning, and persistent state. Read the guide to learn when a managed sandbox makes sense, what capabilities to look for, and how to give agents the tools they need without handing them your infrastructure.

An architectural view of ML.NET
9 minutes by Abdul Rahman

Machine learning in .NET no longer requires Python. ML.NET lets you train and run models using standard C# patterns, keeping everything in one codebase without extra interop layers or separate deployment pipelines. A typical solution splits into three projects: a trainer, a shared schema library, and a client app. You build pipelines by chaining transforms and a trainer, then call Fit once to run the whole thing.

Validation in FastEndpoints: Pipelines, pitfalls, and patterns
14 minutes by Barret Blake

FastEndpoints validators sit between request binding and handler execution, automatically rejecting malformed requests with a 400 response. Validators are singletons, so scoped services like a database context must be resolved inside rules rather than injected through the constructor. Use validators only to check whether input is well formed, and push business rule checks like duplicate names or full party slots into the handler using AddError and ThrowIfAnyErrors. Keeping that boundary clean makes both layers easier to test and reason about.

How to write the fastest code with BenchmarkDotNet
23 minutes by Yoshifumi Kawai

BenchmarkDotNet now pairs well with AI when you add JIT disassembly and branch misprediction counters to your runs. With that richer data, an AI can read machine code directly and iterate on optimizations that go far beyond what most humans would attempt manually. Applied to a MessagePack integer encoder, this approach turned a branchy if-else cascade into a branchless lookup-table design, dropping mixed-input latency from 8.5 ns to 1.6 ns.

BulkSynchronize in EF Core: Mirror your data in one operation
14 minutes by Chris Woodruff

Keeping a database table in sync with an external data source usually means writing fragile, slow code that loads everything into memory just to diff it. BulkSynchronize from Entity Framework Extensions replaces that pattern with a single call that stages data in a temp table and runs a server-side merge covering inserts, updates, and deletes in one transaction. The key detail to get right is scoping the delete branch so it only touches the rows you intend to sync, leaving other data untouched.

And the most popular article from the last issue was:

• How to prevent duplicate API requests in .NET