As a quick upshot, having a managed VNet set up means that any Spark pools you create will have subnet segregation, meaning that the Spark machines will be in their own subnet, away from everything else. This provides a bit of cross-pool protection for you automatically. It also performs similar network isolation for your Synapse workspace, keeping it separated from other workspaces. The other big thing it does is create managed private endpoints to the serverless and dedicated SQL pools, which means that any network traffic between these pools and resources in the Synapse workspace will be guaranteed to transit over Azure networks and not the public internet, at least until it gets to you hitting the web.azuresynapse.net URL (and there are additional methods to lock down that part of it that we won’t cover today).
By default, the portal will not create a managed virtual network, so you’ll need to enable it at creation time. You cannot enable or disable the managed virtual network setting after a workspace has been created, so if you make a mistake, you’d need to rebuild the workspace, though you can at least use the same storage account.
One last thing that managed virtual networks offer you is the ability to enable data exfiltration protection.
Click through to see how it all works. Data exfiltration protection can limit you a bit, and that can be quite frustrating, but it does what it says…in the same way that Draconis did what he said.