Gst on rent of commercial property

Dear Sir, I m a GST registered trader, my goods supply is above 20 lakhs p.a.

my question is A) I pay rent of 8000 for my shop , do I have to pay 18% GST as per rcm on it, in case the landlord is not registered under GST & what if incase he is registered. 

B) I also receive commercial rent from a shop of mine, whose tenant is registered under GST, then in that case who has to pay GST on rent, 

& Will I get ITC on any 1 of them & if yes then on which 1 can I claim back. 

Pls help, Thanks.