What is the phase that not all cells enter, but it is a phase where cells are not actively dividing

The phase that not all cells enter, but is a phase where cells are not actively dividing is called the G0 or non-dividing phase.

G₀ phase

Explanation:

Some types of cells divided slowly or not at all. These cells may exit the G₁ phase and enter a resting phase called G₀ phase. In G₀ phase, a cell is not actively preparing to divide. It's simply doing its job. For some cells, G₀ is a permanent state, while others may restart cell division given the right signals.

i think it is dna, i'm not totally sure but i think it might be.