The Chinese version, cn.alexa.com has been shut down. You can tell this because when you type it in, you get redirected to the main English version of alexa.com.
Founded in 1996 in America, the site ranking site collects more than 1 terabyte of information each day.
In 1999 it was acquired by Amazon.com and set up their Chinese language version in 2010. However, it is now no longer available.