Sub AD group access to sharepoint

We have two AD groups IT_ALL and IT_Paris. IT_Paris is member of IT_ALL in AD. We have given , IT_ALL contribute access on our sharepoint site collection. We expect, IT_Paris to automatically get contribute access as well, becasue we have assigned permission to IT_All, is this expectation correct or we have to explicitly give an access to IT_Paris as well?

After adding IT_All, when i click on Check Permission option and check permission for IT_Paris, it shows NONE. For IT_All it shows contribute.

Please suggest.