The requested URL could not be retrieved

While trying to retrieve the URL: www.oocities.org/hk/ckhmailbox

or trying to send E-mail to : ckhmailbox@yahoo.com.hk

The following error was encountered:

Unable to determine IP address from host name for www.oocities.org/hk/ckhmailbox  

The dnsserver returned:

Name Error: The domain name does not exist.

This means that:

 The cache was not able to resolve the hostname presented in the URL. 
 Check if the address is correct. 
Your cache administrator is root@ln.edu.hk.