D Mixolydian scale on the guitar fretboard

The D Mixolydian scale is made of D (the root), E (major second), F# (major third), G (perfect fourth), A (perfect fifth), B (major sixth) and C (minor seventh). The fretboard shows every one of them across the neck in standard tuning (E A D G B E), and plays them back so you can hear the scale.

The Mixolydian mode is a major scale with a lowered seventh, the fifth mode of the major scale. It shares its notes with a major scale a fifth below, so one set of positions serves both. It is the scale that fits the dominant seventh chord.