When I see answers like this, I add a comment first of all:
Whilst this may theoretically answer the question, it would be
preferable to include the
essential parts of the answer here, and provide the link for
If the link is unreliable (some blog you've never heard of), if it's behind a wall (ubuntu forums login, anything other then the answer), or if it's old, not well written, or it seems wrong, I also downvote the answer.
The comment plus the downvote usually encourage users to write a real answer, based on the link, which is much better.
If on the other hand the link isn't helpful, flag it and use the text-box to let us know why. For example:
Just a link, and it doesn't answer the question
Just a link, and you have to register to read it
If the link is to the answering user's own site and it doesn't answer the question, you're welcome to post a spam-flag rather than moderator attention. You're not forced to tolerate obvious self-promotion.
If the answer behind the link is written by the user, you're welcome to just edit the answer and paste in the whole thing. That is, if the answer isn't subject to copyright restrictions (you are licensing it to AU users, so be careful you have the right to do so).
As always, use your best judgement. Even if a moderator doesn't delete the answer, we may still mark your flag as 'helpful', especially if you've taken the time to leave a comment.
Note also, there is absolutely no shame in reading the link, deciphering the contents and posting an answer of your own, if it really does solve the problem.
In the same way you're encouraged to combine three good answers into one great answer, you're also encouraged to cut, copy and paste together a fantastic solution to a real problem. While, of course, respecting copyright and attributing properly.
See also: Are answers that just contain links elsewhere really "good answers"?