MCSD MCSD Performance Optimization and Scalability 3

Question 1

What is the N+1 query problem in Entity Framework Core and how is it typically resolved?

Accepted Answer

Loading a collection triggers one query per item; resolved by using .Include() for eager loading

Answer

The application makes N database connections before the first result; resolved by connection pooling

Answer

Queries run N times per second before scaling kicks in; resolved by adding more instances

Answer

The ORM generates N redundant indexes; resolved by running a migration

Question 2

In Azure, what does Application Insights help developers do from a performance perspective?

Accepted Answer

Monitor response times, failure rates, and dependencies to identify performance bottlenecks in live applications

Answer

Automatically optimize SQL queries before they reach the database

Answer

Provision additional compute capacity when CPU thresholds are exceeded

Answer

Compress static assets served from Azure Blob Storage

Question 3

What is the purpose of output caching introduced in ASP.NET Core 7 compared to the older Response Caching middleware?

Accepted Answer

Output caching stores responses on the server and supports programmatic invalidation and tagging for finer cache control

Answer

Output caching stores responses in the browser cache instead of the server

Answer

Output caching only applies to static file responses while response caching covers dynamic pages

Answer

Output caching requires Redis while response caching works in-memory only

Question 4

Which .NET garbage collection mode is recommended for server-side ASP.NET Core applications to maximize throughput?

Accepted Answer

Server GC mode, which runs concurrent GC on all available CPU cores

Answer

Workstation GC mode, which pauses the app for full collections

Answer

Concurrent GC with low-latency mode on a single core

Answer

Manual GC calling GC.Collect() after each request

Question 5

What does the Span<T> type in .NET provide that makes it useful for performance-critical code?

Accepted Answer

A stack-allocated view over contiguous memory that avoids heap allocations and GC overhead

Answer

A thread-safe collection type that scales across multiple CPU cores automatically

Answer

A lazily evaluated sequence type similar to IEnumerable<T> but with lower overhead

Answer

A managed pointer to unmanaged memory regions for interop scenarios only

Question 6

In Azure SQL Database, which feature enables automatic tuning to improve query performance over time without manual DBA intervention?

Accepted Answer

Automatic tuning with automatic index management and query plan regression correction

Answer

Elastic Database Pools with auto-DTU scaling per query

Answer

Read Scale-Out replicas for distributing SELECT workloads

Answer

Geo-replication with automatic failover to a secondary region