What should you do?
Keep at or below 100 km/h, leave a safe following distance of at least two seconds, and slow down where conditions demand it.
How to recognise it
A red ring around a black 100 with km/h underneath.
Common confusion
100 km/h is a national road limit; do not confuse it with the 120 km/h motorway limit, which learner permit holders cannot use anyway.
Explanation written by the My Driving Test editorial team using the Department of Transport Traffic Signs Manual conventions and the RSA Rules of the Road.
