The answer is a public IP address resource associated with the VPN gateway. This is the missing prerequisite because an Azure VPN gateway requires a dedicated public IP address to establish the IPsec tunnel with the on-premises VPN device; without it, Azure cannot route traffic over the internet or terminate the VPN connection, causing the deployment to fail during validation. On the AZ-104 exam, this tests your understanding of gateway subnet dependencies and network resource provisioning—a common trap is assuming a dynamic public IP from the VM or load balancer will suffice, but the VPN gateway needs its own static public IP resource explicitly linked. Remember the memory tip: “No PIP, no VPN”—a public IP is the mandatory first step before any gateway can function.
AZ-104 Implement and Manage Virtual Networking Practice Question
This AZ-104 practice question tests your understanding of implement and manage virtual networking. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Exhibit
Azure portal validation output:
Resource group: rg-network
Virtual network: vnet-hub
Subnet: GatewaySubnet exists
Error: The virtual network gateway requires a public IP address to terminate VPN connections.
Based on the exhibit, the VPN gateway deployment fails during validation. What resource is missing?
Azure portal validation output:
Resource group: rg-network
Virtual network: vnet-hub
Subnet: GatewaySubnet exists
Error: The virtual network gateway requires a public IP address to terminate VPN connections.
A
A public IP address resource associated with the VPN gateway.
A VPN gateway needs a public IP resource so the on-premises VPN device can establish encrypted tunnels to Azure. The exhibit already has GatewaySubnet, so the missing piece is the public-facing IP on the gateway itself. Once that resource is created and attached during deployment, the gateway can be provisioned successfully.
B
A network security group attached to GatewaySubnet.
Why wrong: An NSG is not the missing deployment requirement for a VPN gateway and does not provide the public endpoint needed for tunnel termination.
C
A route table with a default route to the on-premises network.
Why wrong: Routing is configured after connectivity exists. A route table does not create the public endpoint required for gateway deployment.
D
A private endpoint for the on-premises VPN device.
Why wrong: Private endpoints are for Azure PaaS services, not for establishing site-to-site VPN tunnels with external devices.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A public IP address resource associated with the VPN gateway.
A VPNgateway requires a dedicated public IP address resource to establish the IPsec tunnel with the on-premises VPN device. During validation, Azure checks that a public IP address is associated with the gateway; if missing, the deployment fails because the gateway cannot route traffic over the internet or terminate the VPN connection.
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.
✓
A public IP address resource associated with the VPN gateway.
Why this is correct
A VPNgateway needs a public IP resource so the on-premises VPN device can establish encrypted tunnels to Azure. The exhibit already has GatewaySubnet, so the missing piece is the public-facing IP on the gateway itself. Once that resource is created and attached during deployment, the gateway can be provisioned successfully.
Related concept
Read the scenario before looking for a memorised answer.
✗
A network security group attached to GatewaySubnet.
Why it's wrong here
An NSG is not the missing deployment requirement for a VPNgateway and does not provide the public endpoint needed for tunnel termination.
✗
A route table with a default route to the on-premises network.
Why it's wrong here
Routing is configured after connectivity exists. A route table does not create the public endpoint required for gateway deployment.
✗
A private endpoint for the on-premises VPN device.
Why it's wrong here
Private endpoints are for Azure PaaS services, not for establishing site-to-site VPN tunnels with external devices.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the requirement for a public IP on the VPNgateway with the need for an NSG or route table on GatewaySubnet, but Azure explicitly blocks NSG association on GatewaySubnet and route tables are optional for site-to-site VPNs.
Detailed technical explanation
How to think about this question
Under the hood, the VPNgateway's public IP address is bound to the gateway's frontend configuration and is used as the source IP for IKE (Internet Key Exchange) phase 1 and phase 2 negotiations. The gateway also requires a dedicated subnet named GatewaySubnet (minimum /27) to host the gateway VMs; without the public IP, the gateway cannot respond to the on-premises VPN device's UDP 500 and 4500 traffic. In a real-world scenario, if you forget to create the public IP resource, the deployment will fail with a validation error like 'The resource Microsoft.Network/publicIPAddresses is not found'.
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 AZ-104 question in full detail.
Implement and Manage Virtual Networking — This question tests Implement and Manage Virtual Networking — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A public IP address resource associated with the VPN gateway. — A VPN gateway requires a dedicated public IP address resource to establish the IPsec tunnel with the on-premises VPN device. During validation, Azure checks that a public IP address is associated with the gateway; if missing, the deployment fails because the gateway cannot route traffic over the internet or terminate the VPN connection.
What should I do if I get this AZ-104 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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Based on the exhibit, a site-to-site VPN gateway deployment fails. What prerequisite should the administrator provide so the gateway can be created successfully?
medium
✓ A.A public IP address resource that will be associated with the VPN gateway.
B.A NAT gateway on the GatewaySubnet to translate tunnel traffic.
C.A private endpoint in the GatewaySubnet for tunnel termination.
D.A network security group that allows inbound TCP 443 to the subnet.
Why A: A site-to-site VPN gateway in Azure requires a public IP address resource to be associated with it for the tunnel to be established. The VPN gateway uses this public IP as the endpoint for on-premises VPN devices to connect to over the internet. Without a public IP, the gateway cannot be provisioned because it has no routable external address for IPsec/IKE negotiation.
Last reviewed: Jun 11, 2026
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This AZ-104 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the AZ-104 exam.
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