':param base_url: The target URL object.
:return: A list of possible domain names that could be hosted in the
same web server that "domain".'

def _get_common_virtualhosts(self, base_url):

    domain = base_url.get_domain()
    root_domain = base_url.get_root_domain()
    common_virtual_hosts = ['intranet', 'intra', 'extranet', 'extra', 'test', 'test1', 'old', 'new', 'admin', 'adm', 'webmail', 'services', 'console', 'apps', 'mail', 'corporate', 'ws', 'webservice', 'private', 'secure', 'safe', 'hidden', 'public']
    for subdomain in common_virtual_hosts:
        (yield subdomain)
        (yield ((subdomain + '.') + domain))
        (yield ((subdomain + '.') + root_domain))
        (yield ((subdomain + '.') + root_domain.split('.')[0]))
