Validating a tenants references

[Nader Hachem]

So i'm currently listening to the biggerpockets book on how to manage rental properties and one point that Brandon brings up is making sure you get references of old landlords for the person you're screening.

Maybe i haven't gotten this far yet and he mentions it later, but how do you know when a potential tenants references are actually their landlords? how are you able to verify they didn't just give you a family members phone number who will just put in the good word?