The D suspended fourth seventh chord is a 4-note chord consisting of the notes D, G, A and C.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as D7sus4.
Chords that are a superset of D7sus4. The chords include more notes but always D, G, A and C.
Chords that are a subset of D7sus4. These contain less notes but all of them are included in D7sus4.
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 D7sus4 chord. Feel free to save or share the image as needed.