blocking web aite acces via host files

is there a way to completly block access to a web site, i mean complete lock out..let's say that i want to block out yahoo, 100%..do i have to edit host with every possible address or can i use a wildcard feature to block any typed or clicked url with yahoo.com in it?

It's a Hosts file, not a domains file. :cool:

You would need to add every host within <domain>.com and all their subdomains.