If an alias extension is used that does not exist in the list of default Search Server extensions (ie., aboutus.aaa), the content using this alias will not be searchable and will not return in any search results. Most standard types are already in thislist, including .aspx, .asp, .htm, .html, and /
When an alias extension is used that does not exist in the list of standard file types, this extension must be added to the list of extensions maintained by Search Server. From the Search Server Administration page,click on "File types". Here, click on "New File Type", and add the extension you are using. Re-run a full crawl to index these pages.