Answer: 24 hours - no; because depending on where you are on Earth, you have a different amount of sunlight.
Explanation:
The day-night cycle is a complete day or a complete rotation of the earth around its axis. This takes 24 hours which is why 24 hours is the length of a full day.
People around the world however, do not get the same amount of sunlight or darkness and this is because of where they are on Earth. Due to the way the planet is tilted on its axis, some areas see sunlight more than other in a period and others see more darkness.