Gst for goods sold to domestic vs foreign buyers.

We are a manufacturing company that'll be making finished goods in India. We will have three types of sales:

1. Sales to domestic buyers, goods shipped from a domestic warehouse.

(In this case, GST will apply)

2. Sales to foreign buyers, goods shipped from a domestic warehouse.

(In this case, there will be no GST as goods will be exported)

3. Sales to foreign buyers, goods shipped from a foreign warehouse.

(What will be the GST liability in this case?)

PS: I Understand that our income will be taxable under normal IT rates in all three cases. My question is about GST.