piano chord
D♭sus4
D♭1G♭4A♭5
The third replaced by the fourth, which leans on the third it is standing in for.
Written the other way round it is C♯sus4 — the same twelve keys on a piano, a different piece of notation.
What is true of it
D♭sus4 is D♭, G♭ and A♭ — 1, 4 and 5 counted from D♭.
These are also the notes of G♭sus2/D♭ and F♯sus2/D♭. Which name is right depends on what is underneath and what came before — the notes alone do not decide.