ASP

Header

301 Moved Permanently

Response.Status="301 Moved Permanently"

you may set up a default error page which content 
the 301 permanent redirect method

Response.AddHeader "Location", URI path

basic 301 can be a way to avoid  404 error message page appear

301 Redirect 主要目的为
永久性重新寻址
改变网址而不会出现「404 找不到网页」将(错误讯息页)设定Response.AddHeader