Interview Q&A

Rate Limiting Middleware in .NET 8

builder.Services.AddRateLimiter(options =>

{

options.GlobalLimiter =

PartitionedRateLimiter.Create<HttpContext, string>(httpContext =>

RateLimitPartition.GetFixedWindowLimiter(httpContext.Connection.Remo

teIpAddress?.ToString()!, _ =>

new FixedWindowRateLimiterOptions

{

PermitLimit = 10,

Window = TimeSpan.FromMinutes(1),

QueueLimit = 2

}));

});

app.UseRateLimiter();

✅ Helps protect APIs from abuse or DoS attacks.

How to Enable Application Insights?

Answer:

Application Insights provides monitoring, telemetry, and tracing.

Setup:

builder.Services.AddApplicationInsightsTelemetry(builder.Configurati

on["APPINSIGHTS_INSTRUMENTATIONKEY"]);

Features:

• Track requests, exceptions, and dependencies
• Live metrics and dashboards
• Custom events and telemetry

How to Use Moq for Mocking Dependencies?

Answer:

Moq creates fake implementations of interfaces to control behavior during tests.

Example:

var mockRepo = new Mock<IProductRepository>();

mockRepo.Setup(x => x.GetAll()).Returns(new List<Product> { new

Product { Id = 1, Name = "Laptop" } });
var service = new ProductService(mockRepo.Object);
var products = service.GetAll();

Assert.Single(products);

✅ Use .Setup(), .Verify(), and .Returns() to simulate behavior.