Interview Q&A

How ASP.NET Core Handles gRPC

• gRPC uses HTTP/2, binary serialization (Protobuf), and strongly typed contracts.
• Add gRPC service:

builder.Services.AddGrpc();

app.MapGrpcService<MyGrpcService>();

• Clients can call server methods over HTTP/2 for high-performance RPC.

Use Cases: Microservices, real-time streaming, low-latency APIs.

Response caching caches the entire HTTP response at the server level — useful for

static or rarely changing API responses.

Setup:

builder.Services.AddResponseCaching();

var app = builder.Build();

pp.UseResponseCaching();

Controller Example:

[ResponseCache(Duration = 60, Location = ResponseCacheLocation.Any)]

[HttpGet]

public IActionResult GetTime() => Ok(DateTime.Now);

✅ The response is cached for 60 seconds — subsequent requests are served faster.

Make sure to set appropriate cache headers in the response.

🚀 6. What is Output Caching in .NET 8?

Output caching (introduced in .NET 8) is an advanced version of response caching that

stores rendered outputs at the middleware level — and supports vary-by, policies, and

uthorization.

Setup:

builder.Services.AddOutputCache();

var app = builder.Build();

pp.UseOutputCache();

Usage:

[OutputCache(Duration = 60, VaryByQueryKeys = new[] { "category" })]

[HttpGet]

public IActionResult GetProducts(string category)
{
return Ok(new { Category = category, Time = DateTime.Now });
}

✅ Benefits:

• Works with authenticated users.
• Supports vary-by parameters, headers, and policies.
• Integrates well with minimal APIs and Razor pages.

🗜 7. How to compress responses?

Use response compression middleware to reduce payload size for clients.

Setup:

builder.Services.AddResponseCompression(options =>

{
options.EnableForHttps = true;

options.Providers.Add<GzipCompressionProvider>();

});

builder.Services.Configure<GzipCompressionProviderOptions>(opt =>

opt.Level = CompressionLevel.Fastest);
var app = builder.Build();

pp.UseResponseCompression();

✅ Compresses responses using Gzip or Brotli automatically.

Common for APIs serving large JSON or text content.

⚙ 8. What is async/await and why is it important in

web apps?

async/await enables non-blocking I/O operations, allowing your web server to handle

thousands of concurrent requests efficiently.

Example:

[HttpGet]

public async Task<IActionResult> GetData()
{
var data = await _service.GetDataAsync(); // Non-blocking call
return Ok(data);
}

✅ Benefits:

• Frees threads while waiting for I/O (e.g., DB, HTTP calls).
• Improves scalability and throughput.
• Essential for high-traffic APIs and cloud-native apps.

❌ Avoid Task.Result or .Wait() — they block threads and reduce performance.

⚡ 9. How to optimize startup performance?

To improve startup and cold-boot performance:

✅ Tips: