At approximately 11 a.m. local time yesterday, Internet users around China reported significant Internet blackouts. Not only were they unable to access some Chinese sites but many foreign Web sites that hadn't previously been blocked were inaccessible as well.
The issue was not isolated to China. Web users in Hong Kong and Japan also reported problems with accessing Chinese sites. A number of explanations immediately came to light, with the most viable cause being the 8.7 magnitude earthquake in Indonesia on Wednesday, which might have damaged undersea cables.
However, reports from China's major telecommunications companies -- China Telecom and Unicom -- suggest that this was not the case. China Telecom confirmed that the earthquake had not interfered with the underwater cables in any way.
Both companies also shot down theories that the outage could have been caused by some sort of blip in the system, with Telecom insisting that there was no issue with its network. Because all Chinese Internet traffic passes through the two networks' infrastructure to get overseas, this had seemed a likely culprit.
With the mystery of what happened becoming murkier, many have been speculating as to what could have caused the blackout.
Read more of "China's mysterious Internet outage; speculation over a 'kill switch'" at ZDNet.