I'd tend to say it's OK, so long as we're pointing at some place with the same semantics as where the author originally had them point. Doc:// and perldoc:// should always end up at some copy of the perl documentation, but it's not important what copy. (That's one reason for the more generic name of doc://.)

While it's possible for the machine to be reachable from some places and not others, that's not a huge worry for me -- for one thing, I'm fairly certian all the machines in question are at pair. What worries me is how we detect "up" and "down". Being able to load a page and get back an "OK" http status does not neccessarly mean that everything is hunky-dory.