Simply copying information, word by word or big chunks of it, without citing the source is wrong. I don't care own you see it or what license the information is shared from.

You should work the information that you obtain, adapt it and fit it to the needs of the site, after you did that you should add a link to the information you based your post on as the source.

Answers that are exact copies of information from other sites should not really exist in a good context, if you can edit them and make some use of that information great, else they should be flagged for moderation and possibly deleted.