How to deal with questions already answered on other communities like Stack Overflow or stats exchange?

Question

I see a lot of questions those are already answered on other communities like StackOverflow or Stats Stackexchange. We can not mark it duplicate as its not on our community. After providing the link to questions its still open, so what to do?

Should mark duplication work across all communities on stackoverflow?

Answer 1

When the question doesn't belong here also, close it for that reason.

When it does, I generally just leave the comment with the link, but if you are worried about the question remaining open, consider summarizing the cross-site answer(s), prominently citing them. You can make your answer community wiki to refrain from reaping any rep benefits.

You might also upvote some meta.SE posts requesting alternative implementations:

• Build and strengthen the Stack Exchange community with "crossover questions" between sites
• Display other SE site links in the linked questions sidebar
• The ability to link cross-site duplicates

See also this cross-meta-site duplicate ;) What to do with cross-site duplicates?