The D flat eleventh chord is a 5-note chord consisting of the notes Db, Ab, Cb, Eb and Gb.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Db11.
Chords that are a superset of Db11. The chords include more notes but always Db, Ab, Cb, Eb and Gb.
Chords that are a subset of Db11. These contain less notes but all of them are included in Db11.
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 Db11 chord. Feel free to save or share the image as needed.