If you configured the virtual network feature during Cosmos DB creation, in this blade you will be able to configure it further. What is more, it is also possible to configure a firewall—so you can restrict access to a specific range of IPs or disallow connections from other Azure data centers. In general, you do not want to have a database that can be accessed by everyone, so if this feature is available, I strongly recommend you use it.
Note that currently firewalls and VNets are available only for the SQL API and Mongo API. Support for other APIs should be available soon.
