Questions & Answers about Собака выглядывает из дома.
In Russian, the preposition из (out of, from inside) always takes the genitive case.
The noun дом (house) in the genitive singular is дома.
Declension of дом (singular):
- Nominative: дом (the house) – subject form
- Genitive: дома (of the house / from the house)
- Dative: дому
- Accusative: дом
- Instrumental: домом
- Prepositional: о доме
Because из requires the genitive, you must say из дома, not из дом.