A good example of how not to answer a “Is it possible to…” question:
It’s ok to admit you don’t know how to do something.
It’s ok to say you don’t think a simple or feasible solution exists for a problem.
It may even be ok to say that something is impossible – if you constrain your answer to current technology. To say this you need to really know the technology, you need to have read about the problem widely enough, and you need to have enough personal experience to be able to say confidently, “no, what you are asking is impossible”. Even then, you might still be wrong, or become wrong sooner or later.
An answer saying outright, “No, that is impossible”, is just inviting a sharp rebuttal. Especially when in the very next sentence you admit that you aren’t an “Oracle specialist” :)