Thank for your advice, Swarnava/Heaven GOD.
But i don't want this url. This is for download for offline update.
my matter is, just now i has use 3rd party software to cut off that pc cannot access to internet. and i have a white-list to key in the url site on white-list menu. and then my pc avast will automatic access to this url get the new definition.
just now i want to know, what is the avast program (update vps url and update virus definition url)?