Genitive Case / षष्ठी विभक्ति (ShaShThii vibhakti): Genitive Case or षष्ठी विभक्ति (ShaShThii vibhakti) of noun-form represents the "whose" of the sentence. In other words genitive case represents the genitive in the sentense. Study the following sentences. These are in genitive case.
In sentence 1 above, if we ask the question "whose son?", the answer that comes is "Dasaratha". So, "Dasaratha" is the genitive in the sentence and the noun-form is in genitive case or ShaShThi vibhakti. Similarly in sentence 4, if we ask the question "whose water?", the answer that comes is "river". So, answer that comes from the question "whose" is the genitive in the sentense and is always in genitive case.Followings are the rules where genitive case is used.