Conditional Hyperlinks

Is it possible to set conditional criteria to hyperlinks? What I'd specifically like to do is check accessibility of a link, if it is accessible go to that link, if not, go to a secondary link. Or if it's not accessible, display a custom message. For example, I have a course with several Intranet links. When working outside the firewall, I cannot access those links. When a learner is taking a course outside the firewall, I'd like to be able to redirect those Intranet links somewhere else or potentially popup a custom message that says something like "The link you are trying to reach is an Intranet link and therefore unavailable if you are not currently working inside the corporate network."