Our practice questions are based on the official exam questions that have appeared on past exams. We have seen many real NCLEX tests and constantly update questions and rationales as regulations change.
Although the National Council of State Boards of Nursing (NCSBN) doesn't make the official tests public, we can confidently say that we know what NCSBN wants to ask on the exam and what topics they want to test you on.
It's very likely that the questions you'll get on the actual exam will be about the same concepts, however, you should be prepared that the questions on the official test will be worded differently. Make sure you read the question carefully and pay special attention to the ones containing a negation or "all/none/some/any of the above" clauses.