First, you must be at least 18 years of age to enter. You can only enter once. And the sweepstakes is open to U.S. residents only. If we could make it open to the entire world, we would. Because ZDNet must obey the law.
Most countries have strict rules about conducting contests to protect citizens.
Unfortunately, the patchwork of different laws makes it impossible to comply with the individual requirements imposed by hundreds of jurisdictions.