By default, the Invoke API assumes RequestResponse invocation type. You can optionally request asynchronous execution by specifying Event as the InvocationType. You can also use this parameter to request AWS Lambda to not execute the function but do some verification, such as if the caller is authorized to invoke the function and if the inputs are valid. You request this by specifying DryRun as the InvocationType. This is useful in a cross-account scenario when you want to verify access to a function without running it.