Step 1: Define the \( x \)-axis.
The \( x \)-axis consists of all points where the coordinates are of the form \( (x, 0, 0) \), where \( x \) is any real number.
Step 2: Foot of the perpendicular.
The foot of the perpendicular from the point \( (0, 1, 2) \) onto the \( x \)-axis represents the closest point on the \( x \)-axis. Since the perpendicular from \( (0, 1, 2) \) to the \( x \)-axis drops to \( x = 0 \), the foot of the perpendicular has the coordinates:
\[
(0, 0, 0).
\]
Step 3: Conclusion.
Thus, the foot of the perpendicular is:
\[
\boxed{(0, 0, 0)}.
\]