title: Proper way to link to a subdomain of the current URL in Drupal
body: <p>What is a proper way to create a link to a subdomain of the current URL, in Drupal 7?</p>
  
  <p>I.e. if I'm on <strong>http://example.com/content123</strong>, the link would point to <strong>http://subdomain.example.com/content123</strong>, thus keeping the current url, only adding a subdomain.</p>