If you know the answer to a question, then answer it.
If you do not know the answer, leave it blank.
- never give an answer that you know to be false
In this case, you know the answer, so answer it.
Since it is possible that a childs surname is different than their fathers surname, the question is (for them) relevent.
Whether it makes sense or not is irrelevant
- they want it, you give it
if not, they may refuse you the visa.
Based on the student visa application found here (german and english)
At the end of the form it is stated:
that the form must be completed to the best of their knowledge and belief
information can lead to refusal of a visa or if found out later expulsion.
In such matters it is wise (in my opinion) to always keep the old saying in mind:
- Ours not to reason why, ours but to do and die