--- title: 35 Senior .NET Developer Interview Questions That... description: A comprehensive set of 35 senior-level .NET interview questions covering runtime internals, GC mechanics, thread pool starvation, production diagnostics,... canonical: https://daily.dev/posts/35-senior-net-developer-interview-questions-that-actually-get-asked--6vcn580bl twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: 35 Senior .NET Developer Interview Questions That Actually Get Asked… | daily.dev og:description: A comprehensive set of 35 senior-level .NET interview questions covering runtime internals, GC mechanics, thread pool starvation, production diagnostics,... og:url: https://daily.dev/posts/35-senior-net-developer-interview-questions-that-actually-get-asked--6vcn580bl og:image: https://api.daily.dev/og/posts/6VCn580bL.png og:image:alt: 35 Senior .NET Developer Interview Questions That Actually Get Asked… og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # 35 Senior .NET Developer Interview Questions That Actually Get Asked… **[Code with Mukesh](https://daily.dev/sources/codewithmukesh)** · [@iammukeshm](https://daily.dev/iammukeshm) · 54 min read · 22 upvotes · 3 comments ## Summary A comprehensive set of 35 senior-level .NET interview questions covering runtime internals, GC mechanics, thread pool starvation, production diagnostics, performance measurement, data-at-scale patterns, and architecture judgment calls. Each question includes a model answer, a red-flag answer to avoid, and a follow-up the interviewer typically chains next. Content is accurate for .NET 10 and C# 14, with specific coverage of DATAS (Dynamic Adaptation To Application Sizes), BinaryFormatter removal timeline, the deprecation of the .NET Upgrade Assistant, and the shift to GitHub Copilot app modernization. The guide emphasizes that senior interviews test diagnostic process and judgment rather than factual recall, and that the strongest answers name a tool, admit uncertainty, and describe the next measurement rather than the next guess. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why is DATAS in .NET important and when was it enabled by default? DATAS (Dynamic Adaptation To Application Sizes) makes the garbage collector size the heap in proportion to an application's live data rather than the machine's total memory, for Server GC only. It was introduced in .NET 8 behind a switch and has been on by default since .NET 9, targeting a 2% throughput cost by default while substantially reducing memory usage. _Teams tracking runtime behavior changes across .NET upgrades can follow GC and performance updates on daily.dev._ ### Was BinaryFormatter removed in .NET 10? No, BinaryFormatter's in-box implementation was removed in .NET 9, not .NET 10. It was obsoleted in .NET 5, became a compile error in .NET 7, started throwing at runtime in .NET 8, and its in-box implementation was fully removed in .NET 9, though an unsupported System.Runtime.Serialization.Formatters package can restore the old, vulnerable behavior. _Developers migrating legacy .NET code off deprecated serialization APIs can track these changes via daily.dev._ ### How do you diagnose thread pool starvation in a .NET API that times out under load with low CPU usage? Thread pool starvation shows up as slow responses combined with idle CPU, typically caused by sync-over-async code blocking pool threads via .Result, .Wait(), or .GetAwaiter().GetResult(). Confirm it with dotnet-counters watching dotnet.thread_pool.thread.count climbing to two or three times the core count while dotnet.thread_pool.queue.length grows and completed work items stay low. _Developers debugging production latency issues in .NET services can find diagnostics workflows like this on daily.dev._ ## Community discussion Top comments from developers on daily.dev. **@rovdev** · 0 upvotes > I have learned a lot from your articles. **@markozakrajsekgeozs** · 0 upvotes > Just by reading the article, I found out that I do not understand the job of senior developers 😊 **@agustinbarrientos** · 0 upvotes > I'd trust a candidate who names the next measurement over one who guesses the root cause with confidence. ## Similar posts on daily.dev - [.NET Interview Questions: The 2026 Guide \(300\+ Real Questions\)](https://daily.dev/posts/net-interview-questions-the-2026-guide-300-real-questions--pahcwviza) · Code with Mukesh · 2 upvotes · 0 comments - [30 .NET System Design Interview Questions That Actually Get Asked in…](https://daily.dev/posts/30-net-system-design-interview-questions-that-actually-get-asked-in--4bxbvg2ew) · Code with Mukesh · 44 upvotes · 3 comments - [30 ASP.NET Core Interview Questions That Actually Get Asked in 2026](https://daily.dev/posts/30-asp-net-core-interview-questions-that-actually-get-asked-in-2026-b4ndnfwkf) · Code with Mukesh · 7 upvotes · 2 comments - [30 LINQ Interview Questions That Actually Get Asked in 2026](https://daily.dev/posts/30-linq-interview-questions-that-actually-get-asked-in-2026-z9bazqvrc) · Code with Mukesh · 13 upvotes · 1 comments - [Five interview answers that sound correct and cost the offer](https://daily.dev/posts/five-interview-answers-that-sound-correct-and-cost-the-offer-dcu6qdrx6) · Medium · 0 upvotes · 0 comments --- Tags: [#performance](https://daily.dev/tags/performance), [#.net](https://daily.dev/tags/.net), [#c#](https://daily.dev/tags/c#), [#interview-questions](https://daily.dev/tags/interview-questions) [View this post on daily.dev](https://daily.dev/posts/35-senior-net-developer-interview-questions-that-actually-get-asked--6vcn580bl) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} 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