"My cat is inside the house."

Translation: Kucing saya ada di dalam rumah.

[tsuj1g1r1]

Is the "ada" obligatory?

[lockers001]

No, but preferable in formal Indonesian.

[nzfleisher]

How is this different than without "dalam"?

[Raekima]

Di dalam rumah = inside the house.
Di rumah = it can be at the house yard, on the roof top, on the fence or of course inside the house, as long as it still around the house