I'm find some links which give messages like:

    Firefox can't find the server at xxx.xxxx.xxx.

I check whether it is down for me or everybody and "It's not just you!". 

Should I edit such questions or answers to make it clear the links are dead?

What if they come back to life?

I'm not sure my question is duplicate of http://meta.askubuntu.com/questions/2229/what-should-we-do-about-answers-with-link-rot because that is for "link only" answers and the link dies.