CHINA (From CNN) -- Internet users in China were met with sluggish response times early Sunday as the country's domain extension came under a "denial of service" attack.
The attack was the largest of its kind ever in China, according to the China Internet Network Information Center, a state agency that manages the .cn country domain.
The double-barreled attacks took place at around 2 a.m. Sunday, and then again at 4 a.m. The second attack was "long-lasting and large-scale," according to state media, which said that service was slowly being restored.
Official state media said the attack targeted websites with the .cn country domain, as well as the popular microblogging site Sina Weibo.
Denial of service attacks aren't technically "hacks," since they can be done without breaking into any systems. Typically, DoS attacks overwhelm a website's servers by flooding them with requests. That makes websites unreachable or unresponsive.
To bring down bigger sites, attackers will sometimes organize large numbers of infected computers to send requests all at once.
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Chinese authorities closely regulate content and websites available to Internet users in the country. The restrictions are extremely sophisticated, leading some to call it a second "Great Wall."
It's unclear whether the attack is related to political events in China, which appears to be in the midst of carrying out a crackdown on Internet dissent.
The government is also wrapping up the trial of former political kingpin Bo Xilai, leading some Internet users in China to note the timing of the attack.
"CN domain name under attack?," one user said on Weibo. "Saw this news and laughed. On every 'festive occasion' doesn't China's Internet become paralyzed?"
Another user lodged a more practical complaint, noting that the sluggish Internet would probably leave many Chinese without sleep.