The Azure production network is segregated into three primary VLANs in a logical manner.
The FC VLAN: It contains supporting systems and trusted Fabric Controllers The Main VLAN: It interconnects the untrusted customer nodes The Device VLAN: It contains a trusted network and all other infrastructure devices Option A is incorrect. The Device VLAN contains a trusted network and all other infrastructure devices.
Option B is incorrect. The main VLAN interconnects the untrusted customer nodes.
Option C is correct. The FC VLAN contains supporting systems and trusted Fabric Controllers.
Option D is incorrect. Azure SQL Database provides a firewall functionality to protect customer data. It's not a type of VLAN.
Reference: To know more about the VLAN Isolation, refer to the link below:
https://docs.microsoft.com/en-us/azure/security/fundamentals/infrastructure-sql