TOW (& Answer)...

The question was when were the bulk of surnames in countries such as England and France formed? The majority were formed in the 13th and 14th centuries.  According to our source “the norm is that in the 11th century people did not have surnames, whereas by the 15th century they did.”  

The question (& answer) were found on p. vii of the introduction to A Dictionary of Surnames by Patrick Hanks and Flavia Hodges.  The book was published by the Oxford University Press in 1988.