Reserved DNS time (Grace period) for different Azure Services

Question

Hi, While reading the following article:

https://learn.microsoft.com/en-us/azure/security/fundamentals/subdomain-takeover#prevent-dangling-dns-entries We can observe "Upon deletion of the classic cloud service resource, the corresponding DNS is reserved for 7 days." This means that cloudapp.net DNS is reserved for seven days before others can take it over. Are there any references as such for other Azure services, such as Azure App Service (azurewebsites.net), Azure VM (cloudapp.azure.com), and Traffic Manager (trafficmanager.net)? I would like to know the timing of which the grace period ends on those products. Thanks a bunch!

Answer 1

@HolyBugx , Apologies for the delay! Thanks for the great question. Yes, there are similar grace periods for other Azure services, including Azure App Service, Azure VM, and Traffic Manager.

For Azure App Service (azurewebsites.net), the DNS name is reserved for 30 days after the app is deleted. Please check these docs. Mitigating subdomain takeovers in Azure App Service :
Having mentioned that, it is recommended to update DNS records before site deletion to ensure bad actors can't take over the domain between the period of deletion and re-creation.
restore-undelete-deleted-web-apps/ba-p/2922088
#prevent-dangling-dns-entries

For Azure VM (cloudapp.azure.com), the DNS name is reserved for 7 days after the VM is deleted. As you highlighted from the Azure doc that you referenced.   For Traffic Manager (trafficmanager.net), the DNS name is reserved for ~2 Hrs after the Traffic Manager profile is deleted. This means that the DNS name cannot be used by another Traffic Manager profile during this period.
As mentioned in the document FAQ: “It can take up to 2 hours for the name to become available after a Traffic Manger profile is deleted.”

It's worth noting that these grace periods are subject to change, so it's always a good idea to check the latest doc for each service to ensure that you have the most up-to-date information. For more info, as additional info - Restore or remove a recently deleted application with the Microsoft identity platform -
“ Neither you nor Microsoft customer support can restore a permanently deleted application or an application deleted more than 30 days ago.”

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