These scales are built upon the 5th degree of a major scale, ie: 5th degree of C scale is the note ‘G’
therefore a C scale starting on the 5th note ‘G’ - would be called ‘G Mixolydian mode’ or G Dominant 7th scale.

dominant-7th scale (mixolydian mode) -5pos-pdf download

dom7th-scales-open-strings pdf download