The D flat dominant seventh chord is a 4-note chord consisting of the notes Db, F, Ab and Cb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Db7.
Chords that are a superset of Db7. The chords include more notes but always Db, F, Ab and Cb.
Chords that are a subset of Db7. These contain less notes but all of them are included in Db7.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the Db7 chord. Feel free to save or share the image as needed.