How to set admin skin of DOTNETNUKE in such way that all admin pages take that theme? I want to use one of admin templates of bootstrap 3 but it seems that dotnetnuke admin pages has its own CSS class which does not match bootstrap class. what should i do?
The individual modules within DNN do have their own styles. Therefore you will not be able to have the actual interactions in those modules use bootstrap styles without making modifications to the core modules
You can set the overall skin on admin pages just like any other page though. The content will be your only item needing work.