Tutorial / Cram Notes
Before diving into troubleshooting, it’s important to have a grasp of the various Azure networking resources. Some of the core components include Azure Virtual Networks (VNets), Network Security Groups (NSGs), Virtual Network Gateways, Public IP addresses, Azure DNS, Load Balancers, and Network Watcher. Each of these plays a role in the external networking capabilities of your Azure environment.
Basic Troubleshooting Steps
Verify Network Security Group (NSG) and Firewall Rules
- Check Inbound and Outbound Rules: Ensure that the rules allow the desired traffic to and from the internet. NSGs can be applied to subnets or individual virtual machines (VMs).
- Service Tags and Application Rules: Use service tags to define network access controls on NSGs or firewall rules.
Review Route Tables
- Analyze the effective routes for a network interface (NIC) to ensure traffic is routed correctly through the Azure fabric. Misconfigured custom routes can redirect traffic in unexpected ways, preventing access to or from external locations.
Check Public IP Addresses
- Confirm that your resources have public IP addresses if they need to communicate with the internet. For VMs, Azure Load Balancer, and Azure Application Gateway, this is a critical setting.
Examine DNS Resolution
- Validate that DNS settings are correctly configured and that the DNS server can resolve external domains if necessary. The Azure DNS service must be properly set up to translate domain names into IP addresses for both inbound and outbound connections.
Advanced Troubleshooting Techniques
Utilize Azure Network Watcher
Azure Network Watcher provides tools for monitoring and diagnosing conditions at a network scenario level. Some helpful tools include:
- IP Flow Verify: Checks if a packet is allowed or denied to or from a VM.
- Next Hop: Determines the next hop for packets sent from a VM.
- Connection Troubleshoot: Tests a connection to a VM or other Azure service.
- Network Performance Monitor: Monitors and analyzes network performance in real-time.
Utilize Azure Monitor and Log Analytics
Azure Monitor can collect, analyze, and act on telemetry data from Azure and on-premises environments. Use it to:
- Set up diagnostics settings and log collection for network resources.
- Analyze log data using queries to identify the root cause of networking issues.
Test Network Latency with Azure Speed Test
For performance-related network issues, Azure Speed Test Tool can help determine latency from different Azure regions to your resource.
Case Examples
Case 1: VM Cannot Connect to External Services
Scenario: An Azure VM is unable to connect to an external service.
Steps:
- Verify NSG rules for outbound traffic.
- Check the effective route table for any misconfigured routes.
- Use Network Watcher’s IP Flow Verify to test if the packets are being blocked.
Case 2: External Users Cannot Access Azure Web App
Scenario: Users report they cannot access a hosted Azure Web App from the internet.
Steps:
- Check that the Azure App Service has a public IP and that DNS settings are correct.
- Confirm that NSG and Azure Firewall rules permit inbound HTTP/HTTPS traffic.
- Investigate Azure Load Balancer configuration if applicable.
By following these troubleshooting steps and utilizing Azure’s robust set of networking tools, administrators can effectively address and resolve external networking issues in their Azure environment, which is an essential competency for the AZ-104 Microsoft Azure Administrator exam.
Practice Test with Explanation
True or False: Azure Network Watcher can be used to diagnose inter-VM connection issues within the same virtual network.
- (A) True
- (B) False
Answer: A) True
Explanation: Azure Network Watcher provides tools that allow you to monitor, diagnose, and gain insights into network performance and health, including inter-VM connection issues within the same virtual network.
Which Azure service can be used to troubleshoot DNS resolution issues?
- (A) Azure Monitor
- (B) Azure Traffic Manager
- (C) Azure DNS
- (D) Azure Network Watcher
Answer: D) Azure Network Watcher
Explanation: Azure Network Watcher’s DNS Lookup feature can be used to troubleshoot DNS resolution issues.
True or False: Azure VPN Gateway allows you to establish secure, cross-premises connectivity.
- (A) True
- (B) False
Answer: A) True
Explanation: Azure VPN Gateway is used to send encrypted traffic between an Azure virtual network and an on-premises location over the public internet, thereby establishing secure, cross-premises connectivity.
If an Azure Load Balancer is not distributing traffic as expected, what could be a possible issue?
- (A) Network Security Group (NSG) configuration issue
- (B) Virtual Network Gateway misconfiguration
- (C) Incorrect DNS settings
- (D) Storage account reaching capacity limit
Answer: A) Network Security Group (NSG) configuration issue
Explanation: An improperly configured Network Security Group (NSG) associated with the VMs or the subnet can prevent traffic from being correctly distributed by the Azure Load Balancer.
True or False: Azure Application Gateway can perform URL-based routing.
- (A) True
- (B) False
Answer: A) True
Explanation: Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications, including URL-based routing.
Which of the following are necessary when troubleshooting a site-to-site VPN connection? (Choose two)
- (A) Gateway logs
- (B) Subscription ID
- (C) Virtual machine sizes
- (D) Gateway configuration settings
Answer: A) Gateway logs and D) Gateway configuration settings
Explanation: Gateway logs and gateway configuration settings are critical when troubleshooting a site-to-site VPN connection, as they can provide detailed insights into the health and configuration of the VPN gateway.
True or False: The “Effective Routes” feature in Azure is used to view and evaluate the effectiveness of marketing campaigns.
- (A) True
- (B) False
Answer: B) False
Explanation: The “Effective Routes” feature in Network Watcher is used to display the list of all effective routes that are applied to an Azure VM, aiding in network troubleshooting, not for evaluating marketing campaigns.
What is the purpose of Azure ExpressRoute?
- (A) To grant express permissions to resources
- (B) To provide a private, dedicated, high-speed connection to Azure
- (C) To express route definitions in Azure DNS
- (D) To accelerate the routing process on the Internet
Answer: B) To provide a private, dedicated, high-speed connection to Azure
Explanation: Azure ExpressRoute allows you to extend your on-premises networks into the Microsoft cloud over a private connection facilitated by a connectivity provider.
True or False: Network Security Group (NSG) flow logs can be used to troubleshoot connectivity issues to and from Azure resources.
- (A) True
- (B) False
Answer: A) True
Explanation: NSG flow logs record all events related to the NSG, which can be used to troubleshoot inbound and outbound connections to Azure resources.
When troubleshooting external networking in Azure, what should you ensure for the public IP address if it’s not reachable?
- (A) It is not in the stopped state.
- (B) It is associated with a resource.
- (C) It is configured to be static.
- (D) It is located in the same region as the related services.
Answer: B) It is associated with a resource.
Explanation: If a public IP address is not reachable, one of the first things to check is whether it is correctly associated with a resource such as a VM or load balancer.
Interview Questions
What is Azure Network Watcher?
Azure Network Watcher is a service that provides monitoring and diagnostic tools for Azure networks.
What are the benefits of using Azure Network Watcher?
Azure Network Watcher provides several benefits, including the ability to monitor network traffic, diagnose connectivity issues, and view network topology.
What are some of the diagnostic tools provided by Azure Network Watcher?
Azure Network Watcher provides several diagnostic tools, including packet capture, IP flow verify, and next hop.
How do you troubleshoot a network security group (NSG) using Azure Network Watcher?
You can use the NSG flow log feature to view traffic through a network security group and identify any issues.
How do you troubleshoot a virtual network gateway using Azure Network Watcher?
You can use the VPN diagnostics feature to diagnose and troubleshoot virtual network gateways.
How do you troubleshoot a virtual machine using Azure Network Watcher?
You can use the connection troubleshoot feature to test connectivity to a virtual machine and diagnose any connectivity issues.
How do you troubleshoot a load balancer using Azure Network Watcher?
You can use the Load Balancer insights feature to monitor the performance and health of a load balancer and troubleshoot any issues.
How do you use the packet capture tool in Azure Network Watcher?
You can use the packet capture tool to capture and analyze network traffic to troubleshoot connectivity issues.
What is the IP flow verify tool in Azure Network Watcher used for?
The IP flow verify tool is used to verify the flow of traffic between virtual machines and identify any connectivity issues.
How can you view network topology using Azure Network Watcher?
You can use the topology feature to view a graphical representation of the network topology in Azure, including virtual machines, virtual networks, and subnets.
What is the next hop tool in Azure Network Watcher used for?
The next hop tool is used to determine the next hop IP address for traffic leaving a virtual machine or a subnet.
How can you use Azure Network Watcher to monitor traffic to and from an Azure virtual machine?
You can use the network security group (NSG) flow logs feature to view traffic to and from an Azure virtual machine.
How do you troubleshoot a DNS issue using Azure Network Watcher?
You can use the DNS diagnostics feature to troubleshoot DNS issues and identify any misconfigurations.
What is the path visualization tool in Azure Network Watcher used for?
The path visualization tool is used to visualize the network path between two virtual machines or subnets.
How can you use the Azure Network Watcher CLI to troubleshoot connectivity issues?
You can use the Azure Network Watcher CLI to perform diagnostic tests, such as testing connectivity to a virtual machine or verifying the flow of traffic through a network security group.
I’ve been having trouble setting up external networking for my Azure VM. Any suggestions?
What are the common issues faced while configuring external networking in Azure?
Thanks for this blog post!
How crucial is it to configure NSGs for troubleshooting external networking?
In my case, the issue was with the DNS settings. Make sure your DNS is properly configured!
I appreciate the details shared in the blog. Thanks!
Can anybody explain the role of Azure Bastion in troubleshooting external networking?
I found that the Azure Network Watcher is invaluable for diagnosing network issues.