Question about vs. Question over

Question about**= Question over*

####Questions about/over something [Longman dictionary]
There are questions about the system’s practicality.

####Uncertainty; doubt: [The free dictionary]
There is no question about the validity of the enterprise.

####Uncertainty; doubt: [Oxford dictionary]
There's no question about whose fault it is.

####Question over/as to/about [Macmillan dictionary]
There had been some question as to whether to interview the boy.

-Both are equal, however, 'question about' is used more than 'question over'! [Refer to Ngram Viewer]

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