What the officer is actually deciding
The consular officer is deciding whether the student is a genuine student — someone whose purpose is to study, who can afford the program, and who has strong ties that will bring them home after graduation. Every question in the interview maps to one of those three tests.
Admission to a good university helps, but it does not answer any of those three questions on its own.
Financial documentation
The student must show that the family can pay for the full cost of the program — tuition, living, and travel — without reliance on unauthorized work in the U.S. Bank statements, income records, and the source of funds all need to be consistent and credible.
Recent large deposits into an account with no supporting income trail are one of the most common reasons visas are refused.
Genuine student, genuine plan
The student should be able to explain, clearly and specifically, why this program at this university makes sense for their goals — and what they plan to do after graduation, in Vietnam or in their next step.
Vague answers, memorized answers, or a program that does not match the student's academic history all raise concern. Preparation for the interview is not about scripting — it is about understanding the student's own file well enough to speak about it naturally.