A storage account must stay reachable through its public endpoint, but only Azure workloads in AppSubnet should be allowed to access it. No private IP is required. What should you configure?
A service endpoint on AppSubnet routes traffic from that subnet to the storage account over the Microsoft backbone while still using the storage account's public endpoint. Adding a corresponding storage firewall VNet rule restricts access so that only requests originating from AppSubnet are allowed, even though the public endpoint remains reachable. This combination satisfies the requirement because the URL/endpoint does not change and no private IP address is introduced, while the firewall rule provides access control based on the subnet's virtual network identity.
Why this answer
A service endpoint on AppSubnet extends the Azure backbone network to the subnet, allowing traffic to the storage account's public endpoint without a private IP. The storage firewall VNet rule then restricts access to only traffic originating from that specific subnet, meeting the requirement of public endpoint reachability with Azure workload-only access.
Exam trap
The trap here is that candidates confuse private endpoints (which remove public endpoint access) with service endpoints (which preserve public endpoint access while restricting traffic), leading them to choose the private endpoint option despite the explicit requirement to keep the public endpoint reachable.
Why the other options are wrong
A private endpoint assigns a private IP to the storage account, which contradicts the requirement that 'no private IP is required' and that the storage account must stay reachable through its public endpoint.
A VPN gateway is used for site-to-site or point-to-site connectivity over the internet, not for allowing Azure workloads in a subnet to access a storage account via its public endpoint. It adds unnecessary complexity and cost, and does not provide the required network-level access control.
The storage account already has a public endpoint; assigning a public IP address is not a configuration option for Azure storage accounts and does not restrict access to AppSubnet.
When would these options actually be correct?
If the question required that the storage account should not be accessible via the public endpoint at all, and only be reachable from AppSubnet using a private IP, then a private endpoint in AppSubnet would be the correct configuration.
A VPN gateway would be correct if the question required connecting an on-premises network to Azure to access a storage account securely over the internet, or if the storage account needed to be accessed from a remote network without using the public internet.
If the question asked for a way to make a storage account accessible via a specific public IP address from on-premises or another cloud, and the storage account firewall allowed that IP, then configuring a public IP (e.g., on a VM or VPN device) could be part of the solution. However, Azure storage accounts do not have a configurable public IP address.
Why candidates pick the wrong answer
Candidates may confuse private endpoints with service endpoints, thinking both provide secure access from a subnet, but private endpoints remove public access and assign a private IP, which is not needed here.
Candidates might think a VPN gateway is needed to securely connect a subnet to a storage account, confusing it with scenarios where private connectivity is required across networks.
Candidates may think that assigning a public IP to the storage account would allow controlling access, confusing storage account public endpoint with a resource that can have a public IP assigned.