The correct answer is to connect the on-premises network to the managed instance's virtual network using ExpressRoute and configure network security group (NSG) rules to restrict inbound traffic to the on-premises subnet. This works because Azure SQL Managed Instance is always deployed inside an isolated virtual network, and ExpressRoute with private peering extends your on-premises network into that VNet over a private, encrypted connection. By then applying NSG rules that allow inbound traffic only from the on-premises subnet’s IP range, you ensure no public endpoint is exposed and only authorized on-premises applications can reach the instance. On the DP-300 exam, this scenario tests your understanding of hybrid connectivity and network security for managed instances—a common trap is assuming a public endpoint with firewall rules is sufficient, but the requirement for a private, encrypted connection demands ExpressRoute. Remember the key pairing: ExpressRoute for private connectivity, NSG for access control. A helpful memory tip is “ExpressRoute extends, NSG restricts.”
DP-300 Implement a secure environment Practice Question
This DP-300 practice question tests your understanding of implement a secure environment. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You have an Azure SQL Managed Instance that needs to be accessed from an on-premises application. The connection must be encrypted and the on-premises network uses an ExpressRoute circuit. You need to configure the managed instance to only accept connections from the on-premises network. What should you do?
Enable a public endpoint and restrict access using a firewall rule.
Why wrong: Public endpoint is less secure and not recommended for private connectivity.
B
Configure a server-level firewall rule to allow the on-premises IP range.
Why wrong: Firewall rules are for public endpoint, which is not enabled.
C
Connect the on-premises network to the managed instance's virtual network using ExpressRoute and configure network security group (NSG) rules to restrict inbound traffic to the on-premises subnet.
ExpressRoute provides private connectivity, and NSGs control traffic within the VNet.
D
Create a private endpoint for the managed instance and configure DNS.
Why wrong: Managed instance is already in a VNet; private endpoint is redundant.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Connect the on-premises network to the managed instance's virtual network using ExpressRoute and configure network security group (NSG) rules to restrict inbound traffic to the on-premises subnet.
Option C is correct because Azure SQL Managed Instance is deployed into a virtual network, and the most secure way to allow only on-premises traffic is to extend the on-premises network into that VNet via ExpressRoute (private peering) and then use Network Security Group (NSG) rules to restrict inbound connections to only the on-premises subnet. This ensures the connection remains private, encrypted (via the ExpressRoute circuit), and does not expose a public endpoint.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Enable a public endpoint and restrict access using a firewall rule.
Why it's wrong here
Public endpoint is less secure and not recommended for private connectivity.
✗
Configure a server-level firewall rule to allow the on-premises IP range.
Why it's wrong here
Firewall rules are for public endpoint, which is not enabled.
✓
Connect the on-premises network to the managed instance's virtual network using ExpressRoute and configure network security group (NSG) rules to restrict inbound traffic to the on-premises subnet.
Why this is correct
ExpressRoute provides private connectivity, and NSGs control traffic within the VNet.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create a private endpoint for the managed instance and configure DNS.
Why it's wrong here
Managed instance is already in a VNet; private endpoint is redundant.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse SQL Managed Instance with Azure SQL Database, incorrectly assuming that server-level firewall rules or private endpoints apply to Managed Instance, when in fact Managed Instance relies entirely on VNet integration and NSG rules for network security.
Detailed technical explanation
How to think about this question
Azure SQL Managed Instance is always injected into a customer-managed subnet within a VNet, and its connectivity is governed by NSG rules and route tables. ExpressRoute with private peering establishes a Layer 3 connection between on-premises and Azure, allowing the on-premises subnet to be treated as part of the VNet. NSG rules can then filter traffic by source IP prefix (the on-premises subnet) and destination port (1433 for SQL), ensuring only encrypted traffic from the on-premises network reaches the managed instance.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-300 question in full detail.
Implement a secure environment — This question tests Implement a secure environment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Connect the on-premises network to the managed instance's virtual network using ExpressRoute and configure network security group (NSG) rules to restrict inbound traffic to the on-premises subnet. — Option C is correct because Azure SQL Managed Instance is deployed into a virtual network, and the most secure way to allow only on-premises traffic is to extend the on-premises network into that VNet via ExpressRoute (private peering) and then use Network Security Group (NSG) rules to restrict inbound connections to only the on-premises subnet. This ensures the connection remains private, encrypted (via the ExpressRoute circuit), and does not expose a public endpoint.
What should I do if I get this DP-300 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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