Requirement of waybill

Dear Experts,

Please clarify the following doubts about waybills.

1. From AP want to make interstate sale. i.e. AP is buyer & other state is Seller, then who has to provide waybill?
2. Is it require to issue waybill for all inter state sale transactions?
3. If possible please provide the section reference for which waybill is not required for some goods etc.?