Define what you mean by "links inside yahoo".
Do you mean all pages for which there is a link to on the page returned by "http://www.yahoo.com"? If so, you could read the HTML returned by an HTTP GET request, and parse through it looking for <a>
elements. You could use the "HTML Agility Pack" for help.
If you mean, "All pages on the server at that domain", probably not. Most websites define a default page which you get when you don't explicitly request one. (for example, requesting http://umair.com almost certainly returns http://umair.com/index.html). Very few website don't define a default, and they will return a list of files.
If you mean, "All pages on the server at that domain, even if they define a default page", no that cannot be done. It would be an extreme breach of security.