What is the primary purpose of using async and await in ASP.NET?
A. To improve the responsiveness and performance of I/O-bound operations by allowing asynchronous execution.
B. To enhance the security of web applications by encrypting data.
C. To manage user authentication and authorization.
D. To optimize database query performance.
Answer: A
Which keyword is used to declare an asynchronous method in C#?
A. async
B. await
C. asynchronous
D. run
Answer: A
What does the await keyword do in an asynchronous method?
A. It pauses the execution of the method until the awaited task completes, without blocking the main thread.
B. It immediately completes the method execution.
C. It terminates the application if the task fails.
D. It synchronously executes the task.
Answer: A
In which context can await be used?
A. Only within methods marked with the async keyword.
B. Anywhere in the application code.
C. In synchronous methods.
D. Only in static classes.
Answer: A
Which type does an asynchronous method return when it does not return a value?
A. Task
B. Task<TResult>
C. void
D. ValueTask
Answer: A
What is the return type of an asynchronous method that returns a value of type int?
A. Task<int>
B. int
C. Task
D. ValueTask<int>
Answer: A
How can you handle exceptions in an asynchronous method?
A. By using try-catch blocks around the await expression.
B. By checking the status of the task manually.
C. By using the async keyword only.
D. By using the finally block exclusively.
Answer: A
What is the effect of calling async methods synchronously using .Result or .Wait()?
A. It can cause deadlocks and block the calling thread, especially in a UI or ASP.NET context.
B. It improves performance by avoiding context switching.
C. It simplifies exception handling.
D. It automatically converts the method to synchronous.
Answer: A
Which of the following is a common mistake when using async and await in ASP.NET applications?
A. Not awaiting asynchronous calls, leading to potential deadlocks and performance issues.
B. Using await in a synchronous context.
C. Declaring non-async methods with async keyword.
D. Handling exceptions using try-catch blocks.
Answer: A
What does the Task.Run method do in an async method?
A. It schedules a task to run on a thread pool and returns a Task that represents the work.
B. It immediately executes the task synchronously.
C. It pauses the execution of the current thread.
D. It creates a new asynchronous method.
Answer: A
How does using ConfigureAwait(false) affect asynchronous code?
A. It prevents the continuation from being marshaled back to the original context, which can improve performance in some scenarios.
B. It ensures that the continuation runs on the original synchronization context.
C. It makes the method execute synchronously.
D. It automatically handles exceptions.
Answer: A
When using await, what happens if the awaited task throws an exception?
A. The exception is captured and can be handled using a try-catch block.
B. The method will terminate without handling the exception.
C. The exception is ignored and the method continues.
D. The exception causes the application to crash immediately.
Answer: A
Which of the following correctly describes async void methods?
A. They are generally used for event handlers and should be avoided in most other scenarios due to lack of proper exception handling and task management.
B. They are preferred for all asynchronous operations.
C. They allow the method to return a value.
D. They automatically manage thread synchronization.
Answer: A
What is the purpose of using ValueTask in asynchronous programming?
A. To reduce allocations when the result is often available synchronously.
B. To manage complex task-based operations.
C. To handle large amounts of data.
D. To perform synchronous operations.
Answer: A
Which keyword is used to declare a method that will perform asynchronous work but does not return a Task or Task<TResult>?
A. async void
B. async Task
C. async Task<TResult>
D. async
Answer: A
What happens if an async method is marked with async but does not contain any await expressions?
A. It still returns a Task, but the method executes synchronously.
B. It causes a compile-time error.
C. It performs an implicit await.
D. It automatically converts the method to synchronous.
Answer: A
Which method should you use to wait for multiple asynchronous operations to complete?
A. Task.WhenAll
B. Task.WhenAny
C. Task.WaitAll
D. Task.WaitAny
Answer: A
How can you handle a situation where you want to continue execution after an asynchronous operation completes, but you do not need the result?
A. By using await with a Task and ignoring the result.
B. By using Task.Run and not awaiting it.
C. By using async void methods.
D. By using Task.Wait.
Answer: A
What is a common use case for async and await in ASP.NET web applications?
A. Performing I/O-bound operations like file access or network requests without blocking the main thread.
B. Handling synchronous database queries.
C. Optimizing client-side JavaScript performance.
D. Managing static file requests.
Answer: A
What is the default behavior of an asynchronous method if no await is used inside it?
A. The method will execute synchronously and return a completed Task.
B. The method will block until it completes.
C. The method will produce a compile-time error.
D. The method will automatically await the operations.
Answer: A
Which method allows you to run an asynchronous operation in parallel and wait for both to complete?
A. Task.WhenAll
B. Task.WhenAny
C. Task.Run
D. Task.WaitAll
Answer: A
What does the await keyword require to work properly in an async method?
A. The method must return a Task or Task<TResult>.
B. The method must be static.
C. The method must handle exceptions using try-catch.
D. The method must not contain any return statements.
Answer: A
Which statement is true about asynchronous programming in ASP.NET?
A. It allows web requests to be processed concurrently, improving scalability and responsiveness.
B. It blocks the server while waiting for I/O operations to complete.
C. It requires all methods to be asynchronous.
D. It reduces the need for database connections.
Answer: A
What happens if an await expression is used in a try block without a corresponding catch block?
A. Any exceptions thrown by the awaited task will propagate up to the calling code.
B. The await expression will be ignored.
C. The exception will be caught and logged automatically.
D. The task will retry automatically.
Answer: A
Which of the following is the correct way to call an asynchronous method from a synchronous context?
A. By using async and await keywords, or by calling .Result or .GetAwaiter().GetResult() with caution.
B. By using a Task.Run method without await.
C. By converting the asynchronous method to synchronous.
D. By calling the method inside a using statement.
Answer: A
What is the primary benefit of using asynchronous programming in web applications?
A. Improved responsiveness and scalability by allowing non-blocking operations.
B. Simplified error handling.
C. Enhanced security features.
D. Reduced code complexity.
Answer: A
Which of the following is a potential drawback of using asynchronous programming?
A. Increased complexity in managing asynchronous flows and potential for introducing bugs.
B. Reduced performance compared to synchronous operations.
C. Lack of support in modern programming languages.
D. Incompatibility with multi-threading.
Answer: A
What is the purpose of Task.Delay in asynchronous programming?
A. To create a delay without blocking the main thread, useful for simulating asynchronous work.
B. To synchronize tasks.
C. To block the thread for a specified duration.
D. To immediately complete a task.
Answer: A
How can you improve performance in an ASP.NET application using asynchronous programming?
A. By freeing up threads to handle more requests concurrently, especially during I/O-bound operations.
B. By reducing the number of active threads.
C. By converting all synchronous methods to asynchronous.
D. By using fewer await statements.
Answer: A
What is a potential issue when mixing synchronous and asynchronous code?
A. It can lead to deadlocks and performance issues if not managed correctly.
B. It simplifies error handling.
C. It automatically improves performance.
D. It reduces code complexity.
Answer: A
When should you prefer async methods over synchronous methods?
A. When performing I/O-bound operations that benefit from non-blocking execution.
B. When all operations are CPU-bound.
C. When working with simple computations.
D. When immediate results are needed without delay.
Answer: A
Which method should be used to execute a piece of code asynchronously but ensure it is awaited when it completes?
A. Task.Run
B. Task.Factory.StartNew
C. Task.Wait
D. Task.Delay
Answer: A
What is the impact of async and await on CPU-bound tasks?
A. They are not ideal for CPU-bound tasks as they do not provide performance benefits and may add overhead.
B. They improve performance by parallelizing CPU-bound work.
C. They simplify the implementation of multi-threading.
D. They reduce CPU usage.
Answer: A
What is the result of not using await with a Task in an async method?
A. The Task will run asynchronously, but any exceptions or results will not be handled properly.
B. The Task will complete synchronously.
C. The method will automatically wait for the Task to complete.
D. The method will not compile.
Answer: A
Which method can be used to create an asynchronous operation that will complete when any of the tasks completes?
A. Task.WhenAny
B. Task.WhenAll
C. Task.Run
D. Task.WaitAny
Answer: A
What does async modifier do when applied to a method?
A. It enables the use of await within the method, allowing it to perform asynchronous operations.
B. It converts the method to a synchronous operation.
C. It restricts the method to be called only from other asynchronous methods.
D. It manages exception handling automatically.
Answer: A
Which of the following is true about asynchronous programming in web servers?
A. It allows for better scalability by freeing up threads while waiting for I/O operations to complete.
B. It always requires multi-threading.
C. It simplifies the application architecture by avoiding the need for load balancing.
D. It eliminates the need for client-side scripting.
Answer: A
What should be considered when using async and await with web requests in ASP.NET?
A. Ensuring that the code does not block the thread and handles the task completion correctly.
B. Avoiding the use of await to improve performance.
C. Using await in synchronous methods.
D. Ignoring exceptions thrown by the asynchronous tasks.
Answer: A
How does asynchronous programming affect the user experience in web applications?
A. It can improve the user experience by making the application more responsive and capable of handling multiple concurrent requests.
B. It always makes the application slower.
C. It reduces the need for user authentication.
D. It requires fewer server resources.
Answer: A