Questions
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1What are dynamic modules in NestJS and when do you use them?
2How would you lazy-load a module in NestJS to improve startup time?
3What are the four properties inside @Module() decorator?
4What is the difference between a shared module and a global module in NestJS?
5What is a NestJS module, and why is it needed?
6What is the difference between exports in a module and making a provider global with @Global()?
7What is the purpose of a module in NestJS and what does the @Module() decorator do?
8Are NestJS modules singletons? What does that mean practically?
9What is a feature module in NestJS and why should you use them instead of putting everything in AppModule?
10Can a feature module re-export an imported module in NestJS? When is this useful?
11What does the @Global() decorator do and how does it change module behaviour in NestJS?
12What are the risks of overusing @Global() modules in NestJS?
13How do you register a global module exactly once in NestJS and what happens if you register it twice?
14What is the naming convention for dynamic module static methods in NestJS and what does each name signal?
15How do you structure a feature module that has sub-features in NestJS?
16What is the difference between a shared module and a global module in NestJS?
17How can a dynamic module expose a forFeature() method that works alongside a forRoot() registration in NestJS?
18What is the module encapsulation rule in NestJS and why does it matter?
19What must the object returned by a dynamic module's static method always include in NestJS?
20What is the difference between imports and providers inside @Module()?
21What is a shared module in NestJS?
22When should you export a module vs export individual providers from a module in NestJS?
23What is a dynamic module in NestJS and how is it different from a static module?
24How do you implement forRootAsync() in a dynamic module so that options can be loaded asynchronously from ConfigService?
25How do you write a dynamic module that supports both sync (register) and async (registerAsync) configuration sharing the same internal providers?
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What is the difference between a shared module and a global module in NestJS?

A shared module makes providers available only to modules that explicitly import it — dependencies are visible and traceable. A global module decorated with @Global() makes providers available everywhere without any import statement — convenient but hides dependencies and makes modules harder to reason about in isolation.

Shared module vs global module
When to use each:
  1. 1

    Shared module — default choice for all feature-level reuse; explicit imports keep the dependency graph readable.

  2. 2

    Global module — only for infrastructure that every single module legitimately needs: config, logging, database.

  3. 3

    Register global modules exactly once in AppModule — never in feature modules.

  4. 4

    Overusing @Global() leads to hidden coupling and makes unit testing harder.