The first attack started Sunday around 2am, followed by a larger attack at 4 a.m.
China has suffered its largest ever cyber attack, crashing servers across the country for about two to four hours.
China’s internet was hit by a major distributed denial of service (DDoS) attack that briefly disrupted and slowed access to sites in the .cn domain, according to the China Internet Network Information Center (CNIIC).
CNIIC apologised to affected users and said it was working to improve "service capabilities", according to the Wall Street Journal.
CloudFlare CEO Matthew Prince was quoted by local media saying, "I don’t know how big the ‘pipes’ of .cn are, but it is not necessarily correct to infer that the attacker in this case had a significant amount of technical sophistication or resources."
The affected sites were up by Monday morning.
This attack has raised concerns about cyber security in China, which is said to have one of the most advanced filtering systems in the world.
A CNNIC spokesman said more details would be shared about the attacks as officials dig deeper.