How do you know the host?
'Padrone' = pa-DROH-neh; 'casa' = KAH-za. Together: 'padrone di casa' is the standard term for host/landlord depending on context.
Classic party or gathering conversation starter. Use when you don't know someone and want to find out how they are connected to the host. It helps you find common ground or mutual friends quickly.
'Padrone di casa' literally means 'master/owner of the house' but in a party context it means 'host.' 'Conoscere' (to know a person) is different from 'sapere' (to know a fact). This is a key A2 distinction.
Sei un amico di Lorenzo?
Are you a friend of Lorenzo's?
More direct — asks specifically about the friendship with the host.
Vi conoscete da tanto?
Have you known each other long?
Good follow-up once you've established how they're connected.
Vi siete conosciuti come?
How did you meet?
Opens up the full story of the connection.
Italian social circles tend to be tight and interconnected. Finding a mutual connection ('un conoscente in comune') at a gathering is deeply satisfying socially and immediately creates trust between strangers.