Wanted to set reverse dns to Azure app service , which configured as custom domain , not by virtual machine

Question

Wanted to set reverse dns to Azure app service , which configured as custom domain , not by virtual machine

Prashant Singh 1

Wanted to set reverse dns to existing azure app service , as dns got blacklisted due to reason "RATS-NoPtr" ,

$pip = Get-AzPublicIpAddress -Name "PublicIp" -ResourceGroupName "MyResourceGroup"
$pip.DnsSettings.ReverseFqdn = "contosoapp1.westus.cloudapp.azure.com."
Set-AzPublicIpAddress -PublicIpAddress $pip

found this cmd , but don't have virtual machine for my app service, so no PublicIP, only custom domian,
If any suggest please let us know

1 answer

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Answer 1

@Prashant Singh

RATS-NoPtr signifies "Reverse Address Tuple Space - No Pointer record." It indicates that a reverse DNS (Domain Name System) lookup for an IP address has failed because there is no PTR (pointer) record associated with the IP address. RATS-NoPtr error in relation to an Azure app service may be because the reverse DNS for the app service's public IP address has not been configured correctly.

Refer more information here
https://learn.microsoft.com/en-us/azure/dns/dns-reverse-dns-for-azure-services

If you don't have a virtual machine for your app service and you are using a custom domain, you can still set the reverse DNS for your app service by creating a CNAME record for your domain that points to your app service's hostname.

Please follow the below steps to configure.

Determine the hostname of your app service. You can find the hostname in the Azure portal by going to the Overview page for your app service and looking for the "URL" field. The hostname will be the portion of the URL that comes after the "https://" prefix.
Go to the domain registrar where you registered your custom domain and log in to the domain management console.
Look for a section or option that allows you to manage DNS records for your domain.
Create a new CNAME record for your domain that points to the hostname of your app service. The CNAME record should have a name that matches your desired reverse DNS value (e.g. "contosoapp1"), and the value should be the hostname of your app service.
Save the CNAME record and wait for it to propagate. It may take some time for the change to take effect, as DNS changes can take up to 72 hours to propagate.

Once the CNAME record has propagated, the reverse DNS for your app service should be set to the desired value.

Prashant Singh 1 Reputation point

2022-12-27T09:22:51.7+00:00

Thanks Arun, for response and detailing it, and it give one direction to investigate it,
Will check with domain registering with CNAME record type.

So if we registar domain name using CNAME record, do we then need to set reverse DNS in app services or it will be set automatically?
Arun Siripuram 911 Reputation points

2022-12-27T10:28:59.033+00:00

@Prashant Singh
If you are using a CNAME record to point your domain name to an Azure App Service, then you do not need to set a reverse DNS (rDNS) record for the App Service. The rDNS record is used to map an IP address to a domain name, and in this case, the domain name is being mapped to the App Service using the CNAME record.

Please "Accept the answer" if the information helped you. This will help us and others in the community as well.
Prashant Singh 1 Reputation point

2022-12-28T10:29:24.61+00:00

Thanks Again for your quick response, Sure will make it "Accept Answer",
Just I need to check with my client partner for entryof DNS registery, whether its CNAME or not

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Wanted to set reverse dns to Azure app service , which configured as custom domain , not by virtual machine

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