02 ‐ Azure Scenario based questions - SanjeevOCI/Study GitHub Wiki

Here are scenario-based questions covering Azure networking components such as Internet Gateway (Azure equivalent: Public IP + NSG), NAT Gateway, Service Endpoint, Private Endpoint, VPN Gateway, and ExpressRoute:

Scenario-Based Questions for Azure Networking

1. Internet Gateway Equivalent (Public IP + NSG)

Scenario:
You have deployed a Virtual Machine (VM) in Azure and need to make it accessible to the internet for hosting a public-facing web application.

  • Question:
    • What steps would you take to make the VM accessible to the internet while ensuring security?
  • Expected Answer:
    • Assign a Public IP to the VM's network interface.
    • Configure an Inbound Security Rule in the Network Security Group (NSG) to allow HTTP (port 80) and HTTPS (port 443) traffic.
    • Restrict access to specific IP ranges if needed for enhanced security.

2. NAT Gateway

Scenario:
You have a private subnet in a Virtual Network (VNet) where VMs need to access the internet to download updates, but they should not be accessible from the internet.

  • Question:
    • How would you configure the network to allow outbound internet access while keeping the VMs private?
  • Expected Answer:
    • Deploy a NAT Gateway and associate it with the private subnet.
    • Update the Route Table for the subnet to route all outbound traffic (0.0.0.0/0) through the NAT Gateway.
    • Ensure no Public IP is assigned to the VMs.

3. Service Endpoint

Scenario:
You have a VM in a private subnet that needs to access Azure Storage securely without exposing the storage account to the public internet.

  • Question:
    • How would you configure the network to allow secure access to Azure Storage?
  • Expected Answer:
    • Enable Service Endpoint for Azure Storage on the subnet.
    • Update the Storage Account Firewall to allow traffic only from the VNet with the Service Endpoint enabled.
    • Ensure no Public IP is required for the VM.

4. Private Endpoint

Scenario:
You have an Azure SQL Database that needs to be accessed securely from a VM in a private subnet without exposing the database to the public internet.

  • Question:
    • How would you configure the network to allow secure access to the Azure SQL Database?
  • Expected Answer:
    • Create a Private Endpoint for the Azure SQL Database in the same VNet as the VM.
    • Update the DNS settings to resolve the database's private endpoint.
    • Ensure the VM and the private endpoint are in the same or peered VNets.

5. VPN Gateway

Scenario:
Your on-premises data center needs to connect securely to an Azure VNet to access resources like VMs and databases.

  • Question:
    • How would you configure the network to establish secure connectivity between on-premises and Azure?
  • Expected Answer:
    • Deploy a VPN Gateway in the Azure VNet.
    • Configure a Site-to-Site VPN connection between the on-premises VPN device and the Azure VPN Gateway.
    • Ensure the on-premises subnet and Azure VNet do not overlap.

6. ExpressRoute

Scenario:
Your organization requires a high-speed, low-latency, and private connection between on-premises and Azure for critical workloads.

  • Question:
    • How would you configure the network to meet these requirements?
  • Expected Answer:
    • Set up an ExpressRoute Circuit with a connectivity provider.
    • Link the ExpressRoute Circuit to the Azure VNet using a Virtual Network Gateway.
    • Configure routing between on-premises and Azure using BGP.

7. Hub-and-Spoke Architecture

Scenario:
You need to design a network where multiple VNets (spokes) can communicate with each other through a central VNet (hub).

  • Question:
    • How would you implement this architecture in Azure?
  • Expected Answer:
    • Create a Hub VNet with a VPN Gateway or ExpressRoute Gateway for external connectivity.
    • Peer the spoke VNets with the hub VNet using VNet Peering.
    • Use User-Defined Routes (UDRs) in the spoke VNets to route traffic through the hub.

8. Load Balancer

Scenario:
You have deployed multiple VMs in a VNet to host a web application. You need to distribute incoming traffic evenly across these VMs.

  • Question:
    • How would you configure the network to achieve this?
  • Expected Answer:
    • Deploy an Azure Load Balancer.
    • Add the VMs to the Backend Pool of the Load Balancer.
    • Configure Health Probes to monitor VM availability.
    • Create a Load Balancer Rule to forward traffic (e.g., HTTP/HTTPS) to the backend pool.

9. Application Gateway

Scenario:
You need to host a web application with SSL termination and application-layer routing.

  • Question:
    • How would you configure the network to meet these requirements?
  • Expected Answer:
    • Deploy an Azure Application Gateway.
    • Configure SSL termination by uploading the SSL certificate to the Application Gateway.
    • Set up HTTP settings and listeners to route traffic to the backend pool.
    • Use WAF (Web Application Firewall) for additional security.

10. Traffic Manager

Scenario:
You have deployed your application in multiple Azure regions and need to route user traffic to the nearest region for better performance.

  • Question:
    • How would you configure the network to achieve this?
  • Expected Answer:
    • Deploy Azure Traffic Manager.
    • Configure a Traffic Manager Profile with endpoints for each region.
    • Use the Performance Routing Method to direct users to the nearest endpoint.

11. NSG vs. Azure Firewall

Scenario:
You need to secure traffic to and from your VMs in a VNet. You are considering using either NSGs or Azure Firewall.

  • Question:
    • What are the differences between NSGs and Azure Firewall, and when would you use each?
  • Expected Answer:
    • NSG: Filters traffic at the subnet or NIC level. Use for basic traffic filtering.
    • Azure Firewall: A centralized, stateful firewall for advanced filtering, including FQDN filtering and threat intelligence. Use for complex security requirements.

12. Peering Between VNets

Scenario:
You have two VNets in the same region that need to communicate with each other.

  • Question:
    • How would you configure the network to enable communication between the VNets?
  • Expected Answer:
    • Use VNet Peering to connect the VNets.
    • Ensure the address spaces of the VNets do not overlap.
    • Update the NSGs to allow traffic between the VNets.

13. Forced Tunneling

Scenario:
You want all internet-bound traffic from your Azure VMs to be routed through your on-premises network for inspection.

  • Question:
    • How would you configure the network to achieve this?
  • Expected Answer:
    • Configure Forced Tunneling by setting up a VPN Gateway or ExpressRoute Gateway.
    • Update the Route Table to send 0.0.0.0/0 traffic to the on-premises gateway.

14. Azure Bastion

Scenario:
You need to securely access a VM in a private subnet without exposing it to the internet.

  • Question:
    • How would you configure the network to achieve this?
  • Expected Answer:
    • Deploy Azure Bastion in the same VNet as the VM.
    • Use the Azure Portal to connect to the VM via Bastion without requiring a public IP.

15. Monitoring and Diagnostics

Scenario:
You need to monitor and troubleshoot network traffic in a VNet.

  • Question:
    • What tools would you use to monitor and diagnose network issues in Azure?
  • Expected Answer:
    • Use Network Watcher for packet capture, connection troubleshooting, and NSG flow logs.
    • Enable Azure Monitor for metrics and alerts.

These scenario-based questions cover a wide range of Azure networking components and their practical use cases, helping to assess both theoretical knowledge and hands-on experience.

Azure Networking Scenario-Based Questions with Answers

  1. Internet Access & NAT Gateway Q: Your Azure VM in a private subnet needs to access the internet but shouldn’t be accessible from outside. How will you configure this? A: Attach a NAT Gateway to the subnet. This allows outbound internet access while keeping inbound access blocked. Ensure NSG allows outbound traffic.

Q: What is the difference between NAT Gateway and a Public IP associated with a VM? A: NAT Gateway provides outbound-only internet access for multiple resources in a subnet. Associating a Public IP gives both inbound and outbound access to that specific VM.

  1. VPN Gateway & ExpressRoute Q: Your on-premises data center needs to connect securely to Azure. Explain how you would choose between VPN Gateway and ExpressRoute. A: Use VPN Gateway for cost-effective, quick setup over the internet. Use ExpressRoute for high performance, dedicated private connection with higher SLAs.

Q: How would you set up active-active VPN Gateway for high availability? A: Enable active-active configuration in VPN Gateway and configure BGP routing with multiple on-premises devices.

  1. Service Endpoints & Private Endpoints Q: Your app service in one VNet needs to access Azure Storage securely. Which option would you use: Service Endpoint or Private Endpoint? A: Use Private Endpoint for enhanced security as it maps a private IP within the VNet directly to the Azure Storage service.

Q: Can you explain a scenario where Private Link causes DNS resolution issues and how you'd troubleshoot it? A: If custom DNS is used but not configured to resolve the privatelink FQDN, the service won’t resolve. Use Azure Private DNS Zone and link it to the VNet to fix.

  1. NSG & Azure Firewall Q: How would you restrict traffic between two subnets within a VNet? A: Apply NSGs on each subnet with rules to allow or deny traffic between them based on IP, port, and protocol.

Q: NSG is allowing traffic but the VM is not reachable. How do you troubleshoot? A: Check if the UDRs are misrouted, VM firewall rules, or if there is a conflict with Azure Firewall or appliance blocking traffic.

  1. User-Defined Routes (UDR) Q: You have an Azure Firewall in a hub VNet. How will you ensure all traffic from spoke VNets passes through it? A: Configure UDRs in spoke VNets with next hop as Azure Firewall IP. Use VNet peering with traffic forwarding enabled.

Q: Can you create a route that overrides the system route to the internet? A: Yes. UDR with 0.0.0.0/0 can override system default route if set with a next hop to NVA or Firewall.

  1. VNet Peering & Global Peering Q: Two VNets in different subscriptions and regions need to communicate. How would you implement that? A: Use Global VNet Peering and ensure both subscriptions have permissions to establish peering. Configure necessary NSG and route rules.

Q: Can you route traffic from VNet A to VNet C via VNet B using peering? A: No, transitive peering is not supported. Use a hub VNet or Route Server with NVA for transit routing.

  1. Azure Route Server / NVA Integration Q: Your Azure deployment needs dynamic BGP routing with a third-party NVA. How would you architect that in Azure? A: Deploy Azure Route Server in the VNet and establish BGP session with the NVA. Ensure subnet for Route Server is /27 and not used by any other resource.

Q: Can you integrate Azure Route Server with a VPN appliance? A: Yes, if the VPN appliance supports BGP. You can advertise prefixes dynamically without static UDR updates.

  1. Load Balancer & Application Gateway Q: Design a solution where your web app is protected using WAF and supports session persistence. A: Use Azure Application Gateway with WAF enabled and cookie-based affinity for session persistence.

Q: How do you configure end-to-end SSL using Application Gateway? A: Upload SSL certificate to the gateway, enable HTTPS listener, and configure backend pool with HTTPS probes.

  1. Hub-and-Spoke Architecture Q: How will you implement a secure and scalable hub-and-spoke network in Azure? A: Create a hub VNet with shared services (NVA, Firewall, DNS). Peer spoke VNets to the hub. Use NSG, UDR, and route all traffic via hub Firewall for inspection.

  2. DNS Resolution Across VNets Q: A VM in VNet1 needs to resolve a private link service hosted in VNet2. How will you make DNS work? A: Use Azure Private DNS Zone linked to both VNets or set up a custom DNS server that can resolve private endpoint FQDNs.