"In examinations, the foolish asks questions the wise cannot answer" What did Oscar Wilde mean by this?

It has multiple interpretations. Two very popular are the following:

1- It's a funny quotation, that the examiners ask the questions which they don't know themselves.

Here I want to share a joke;

A young boy joined a new school. After a few days his mother asked him. 

Mother: How is your school going on?

Boy: It's OK.

Mother: How is your new teacher?

Boy: Alright, but she answers simple questions by herself and ask the harder ones from us.

2- This quotation has a deep meaning. 

No one has the absolute wisdom. Asking  questions by the Examiners doesn't mean that they have the ultimate knowledge. Similarly if  the students can't reply all the questions does not make them absolute fools.

There are so many questions asked frequently by the fools which don't have any answer.

Example:

 Hen was the first or egg?

Hello, it can be said that it is family questions until the miraculous answers are rejected and that kiss is not really called an award when the owner is considered a loss when the loser