As a fallback for standard UDP DNS over IPv4, they do use your IP address in a rather clever way: they have multiple IPv4s so you can have different rule sets f

As a fallback for standard UDP DNS over IPv4, they do use your IP address in a rather clever way: they have multiple IPv4s so you can have different rule sets for different devices under the same IPv4 and they identify which ones by linking the two addresses together (NET1->DNS1 gets RULES1, NET1->DNS2 gets RULES2, etc.).