Explanation:
To ensure that only VM1 can access DB1 - A private endpoint
A private endpoint provides a secure connection to your Azure SQL Database by creating a private IP address that is only accessible from your internal network (i.e., the virtual network connected to Subnet1), ensuring that the database is inaccessible from the internet.
To enforce network security restrictions for DB1 - Virtual network rules Virtual network rules allow you to control access to your Azure SQL Database by setting specific rules for which subnets or IP addresses can access the database. This option ensures that access to DB1 is restricted to VM1, and it prevents access from other machines or the internet.