Entity Framework handles validation errors during the SaveChanges() method execution by throwing a DbEntityValidationException when there are validation errors encountered. This exception contains details about the validation errors, such as the entity, property, and error message, which can be used for debugging and handling errors gracefully.

The most common place to add validation logic for entity properties in Entity Framework is within the setters of entity properties, ensuring that data is validated before it is set on the entity.

Data Annotations in Entity Framework enable automatic validation of entities by applying attributes to entity properties, defining validation rules that are checked before saving data to the database.

Model validation in Entity Framework primarily aims to ensure that the data being saved to the database adheres to predefined business rules and constraints, thus maintaining data integrity.

Table Splitting allows you to separate frequently accessed properties from less frequently accessed ones into separate tables. This optimization reduces data retrieval overhead by minimizing the amount of unnecessary data fetched from the database, thus enhancing performance for specific queries.

Table Splitting allows splitting related properties of an entity into separate tables, enabling better data normalization by reducing redundancy. This separation ensures that each table represents a distinct entity, thereby contributing to improved data integrity and reducing data redundancy.

Data Annotations are a set of attributes in .NET that can be applied to model properties to define validation rules. Custom Validation Attributes allow developers to define custom validation logic tailored to specific requirements.

The correct option is option 4: DataAnnotations. Entity Framework integrates with DataAnnotations to enable automatic validation based on model annotations during the model binding process. DataAnnotations provides a set of attributes that can be applied to model properties to specify validation rules. These annotations are used by Entity Framework to perform automatic validation during model binding in ASP.NET MVC and ASP.NET Core applications. ASP.NET Core and ASP.NET MVC are web frameworks, and FluentValidation is a third-party validation library that can also be used with Entity Framework, but it is not integrated by default for automatic validation based on model annotations.

The correct option is option 1: DataAnnotations. DataAnnotations is a namespace in .NET that provides attributes that can be applied to model properties to specify validation rules. These annotations are used by Entity Framework to generate client-side validation scripts automatically based on the model's properties. ModelState and ValidationContext are related to server-side validation, and ModelState.IsValid is a property used to check if the model state is valid in ASP.NET MVC applications.

The correct option is option 4: ValidateEntity. This method can be overridden in the DbContext class to provide custom validation logic before saving changes to the database. It allows developers to perform validation on individual entities before they are saved. OnModelCreating is used to configure the model and its relationships, whereas OnSaveChanges is not a method available for customization in DbContext.

A best practice for implementing server-side validation in a distributed application using Entity Framework is to create a centralized validation service. This service can encapsulate all validation logic, ensuring consistency across the application. By separating validation concerns into a dedicated service, you promote code reuse and maintainability. Additionally, you can leverage dependency injection to inject the validation service into relevant components, such as controllers or business logic classes, allowing for easy integration and testing.

Entity Framework provides the DbContext.ValidateEntity method, which allows you to trigger revalidation of the entity's state at various points in your application. This method can be overridden in your custom DbContext class to implement additional validation logic or to trigger revalidation based on specific conditions. By calling this method, you can ensure that the model's state is revalidated according to your requirements, providing flexibility in managing validation in different scenarios.