Port listener windows

Skip to main content This browser is no longer supported. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Configure a DNN listener for an availability group Article06/18/2024 In this article -->Applies to: SQL Server on Azure VMWith SQL Server on Azure VMs in a single subnet, the distributed network name (DNN) routes traffic to the appropriate clustered resource. It provides an easier way to connect to an Always On availability group (AG) than the virtual network name (VNN) listener, without the need for an Azure Load Balancer.This article teaches you to configure a DNN listener to replace the VNN listener and route traffic to your availability group with SQL Server on Azure VMs for high availability and disaster recovery (HADR).For an alternative connectivity option, consider a VNN listener and Azure Load Balancer instead.OverviewA distributed network name (DNN) listener replaces the traditional virtual network name (VNN) availability group listener when used with Always On availability groups on SQL Server VMs. This negates the need for an Azure Load Balancer to route traffic, simplifying deployment, maintenance, and improving failover.Use the DNN listener to replace an existing VNN listener, or alternatively, use it in conjunction with an existing VNN listener so that your availability group has two distinct connection points - one using the VNN listener name (and port if non-default), and one using the DNN listener name and port.CautionThe routing behavior when using a DNN differs when using a VNN. Do not use port 1433. To learn more, see the Port consideration section later in this article.PrerequisitesBefore you complete the steps in this article, you should already have:SQL Server starting with either SQL Server 2019 CU8 and later, SQL Server 2017 CU25 and later, or SQL Server 2016 SP3 and later on Windows Server 2016 and later.Decided that the distributed network name is the appropriate connectivity option for your HADR solution.Configured your Always On availability group.Installed the latest version of PowerShell.Identified the unique port that you will use for the DNN listener. The port used for a DNN listener must be unique across all replicas of the availability group or failover cluster instance. No other connection can share the same port.NoteIf you have multiple AGs or FCIs on the same cluster and you use either a DNN or VNN listener, then each AG or FCI needs its own independent connection point.Create scriptUse PowerShell to create the distributed network name (DNN) resource and associate it with your availability group.To do so, follow these steps:Open a text editor, such as Notepad.Copy and paste the following script:param ( [Parameter(Mandatory=$true)][string]$Ag, [Parameter(Mandatory=$true)][string]$Dns, [Parameter(Mandatory=$true)][string]$Port)Write-Host "Add a DNN listener for availability group $Ag with DNS name $Dns and port $Port"$ErrorActionPreference = "Stop"# create the DNN resource with the port as the resource nameAdd-ClusterResource -Name $Port -ResourceType "Distributed Network Name" -Group $Ag # set the DNS name of the DNN resourceGet-ClusterResource -Name $Port | Set-ClusterParameter -Name DnsName -Value $Dns # start the DNN resourceStart-ClusterResource -Name $Port$Dep = Get-ClusterResourceDependency -Resource $Agif ( $Dep.DependencyExpression

The primary replica through the listener with Windows authentication:sqlcmd -S -EIf the listener is using a port other than the default port (1433), specify the port in the connection string. For example, the following sqlcmd command connects to a listener at port 1435:sqlcmd -S ,1435 -EThe SQLCMD connection automatically connects to whichever instance of SQL Server hosts the primary replica.NoteMake sure that the port you specify is open on the firewall of both SQL Servers. Both servers require an inbound rule for the TCP port that you use. For more information, see Add or Edit Firewall Rule.If you're on the secondary replica VM, and you're unable to connect to the listener, it's possible the probe port was not configured correctly.You can use the following script to validate the probe port is correctly configured for the availability group:Clear-HostGet-ClusterResource `| Where-Object {$_.ResourceType.Name -like "IP Address"} `| Get-ClusterParameter `| Where-Object {($_.Name -like "Network") -or ($_.Name -like "Address") -or ($_.Name -like "ProbePort") -or ($_.Name -like "SubnetMask")}Guidelines and limitationsNote the following guidelines on availability group listener in Azure using internal load balancer:With an internal load balancer, you only access the listener from within the same virtual network.If you're restricting access with an Azure Network Security Group, ensure that the allow rules include:The backend SQL Server VM IP addressesThe load balancer floating IP addresses for the AG listenerThe cluster core IP address, if applicable.Create a service endpoint when using a standard load balancer with Azure Storage for the cloud witness. For more information, see Grant access from a virtual network.PowerShell cmdletsUse the following PowerShell cmdlets to create an internal load balancer for Azure Virtual Machines.New-AzLoadBalancer creates a load balancer.New-AzLoadBalancerFrontendIpConfig creates a front-end IP configuration for a load balancer.New-AzLoadBalancerRuleConfig creates a rule configuration for a load balancer.New-AzLoadBalancerBackendAddressPoolConfig creates a backend address pool configuration for a load balancer.New-AzLoadBalancerProbeConfig

The Win + R keys.Type “services.msc” and click OK to open Windows services.Type in services.mscRight-click on Cryptographic services and open its properties.Opening cryptographic services propertiesChange the Startup type to “Disabled.”Click on Apply and OK. Disabling the service8. Change the default Windows port numberWindows has a default port number for the Hyper-V and Virtual Machine connectivity. When Windows fails to communicate with that port number, it fails to connect to the Virtual Machine. Changing this port number is known to fix connectivity errors. Therefore, you can change your default port number with the following instructions:Turning off the virtual machineRight-click on the Virtual Machine.Select the “Turn off” option on the context menu.Turning off the virtual machineChecking port numberOpen the run command with the Win +R keys.Type “regedit” and click OK to open the registry editor.Opening registry editor Navigate to the following path:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\VirtualizationNow, check the Listener port number on the right pane.Verifying listener port numberVerifying port number connectionOpen the Windows start menu with the Win key.Type “cmd” and run it as an administrator.Type the following command and press Enternetstat -ano | find "2179"Verifying port connectionThe command fails to run which indicates that Windows has failed to connect to the Port.Changing Port numberMinimize the command prompt and return to the Registry Editor.Right-click on the Listener Port Registry key and select modify. Modifying the registry keyChange the value to “21791” and select the Decimal radio button.Click OK to apply the changes.Changing value dataRestarting the serviceOpen the Windows start menu and type “PowerShell.”Run “Windows Powershell” as an administrator.Type the following commands to restart the virtual machine services:stop-service vmmsstart-service vmmsRestarting the Virtual machine serviceOpen the minimized command prompt (as an administrator)Type the following command and press Enternetstat -ano | find "21791"Changing the state of the portWhen both TCPs are “LISTENING”, you can launch the Virtual Machine. Muhammad Zubyan Muhammad Zubyan is a certified Google IT Support Professional with over 7 years of extensive experience. He has worked on more than 1500 computers, gaining valuable insights that enable him to detect and troubleshoot any complicated root cause of Windows-related issues and errors. In addition to managing Appuals as a Senior Editor, he is currently developing his own Game Optimization program that caters to both gamers and casual users alike.