The Dominant Pentatonic is considered a modal pentatonic scale. A modal pentatonic scale is created when two notes are removed from a seven note scale.

The five notes left over are usually chord tones plus one or two characteristic sounding notes from the original scale.In this case our original scale is Mixolydian and we chose the root, second, major third, perfect fifth, and minor seventh as our notes.

Another version of Dominant Pentatonic adds the perfect fourth in place of the second.

The Modes of the Dominant Pentatonic Scale