I have added a sub-domain to my domain. But there is a different results when I add www to the URL. For example, when I type http://XXX.yyyyy.com and http://www.XXX.yyyy.com the results is different. xxx is the sub-domain and yyyy is the domain. http://www.xxx.yyyy.com will show the page of www.yyyy.com.
Moreover, many times, the web sites stored in the server of hosting company will changed. They said that there is a proxy server of my server provider of internet but their fault. Is it right?