On premise and Azure naming conventions and reserved resource names do collide, when you do an Azure Arc Onboarding with an ReservedResourceName error. It is important to remember the Azure naming convention / reserved resource names.

Issue and symptoms

If you are getting an error message during Azure Arc onboarding or create an Azure resource with this content “ReservedResourceName” or the message “The resource name or a part of the name is a trademarked or reserved word” you most likely encountered a rare issue. Some names or part of names cannot be used for Azure Resources. The full list is available here.

Azure Reserved Resource names

Check this link for the current version of the reserved names and avoid issues with “ReservedResourceName”.

Reserved Words

Please be aware that resources with an accessible endpoint, like a fully qualified domain name, can’t use reserved words or trademarks in the name. There is a check when resources are created. This is true, even if the endpoint isn’t currently enabled.

The following words are reserved:

• ACCESS
• APP_CODE
• APP_THEMES
• APP_DATA
• APP_GLOBALRESOURCES
• APP_LOCALRESOURCES
• APP_WEBREFERENCES
• APP_BROWSERS
• AZURE
• BING
• BIZSPARK
• BIZTALK
• CORTANA
• DIRECTX
• DOTNET
• DYNAMICS
• EXCEL
• EXCHANGE
• FOREFRONT
• GROOVE
• HOLOLENS
• HYPERV
• KINECT
• LYNC
• MSDN
• O365
• OFFICE
• OFFICE365
• ONEDRIVE
• ONENOTE
• OUTLOOK
• POWERPOINT
• SHAREPOINT
• SKYPE
• VISIO
• VISUALSTUDIO
• WEB.CONFIG
• XBOX

The following word can’t be used at the start of a resource name, but you can use it in the middle or the end.

• LOGIN

Reserved words – even substring

The following two words are not allowed, even as a substring

• MICROSOFT
• WINDOWS

Naming convention Active Directory and DNS

There is also a naming convention for NetBIOS computer names, DNS host names, NetBIOS domain names, DNS domain names, Active Directory Site names and OU names.

Windows domain name system (DNS) supports Unicode characters. Other implementations of DNS don’t support Unicode characters. Avoid Unicode characters if queries will be passed to the servers that use non-Microsoft implementations of DNS. For more information, see the following RFCs:

• RFC 952: DOD Internet Host Table Specification
• RFC 1123: Requirements for Internet Hosts–Application and Support

A generic advice is to avoid any special characters for Active Directory and DNS. I do use “-” and “_”, but avoid these:

• Disallowed characters: DNS domain names can’t contain the following characters:
• comma (,)
• tilde (~)
• colon (:)
• exclamation point (!)
• at sign (@)
• number sign (#)
• dollar sign ($)
• percent (%)
• caret (^)
• ampersand (&)
• apostrophe (‘)
• period (.)
• parentheses (())
• braces ({})
• underscore (_)
• white space (blank) Note

Conclusion

Pay attention to naming conventions to avoid issues like the “ReservedResourceName”. Avoid challenges by planning your environment carefully. There are a lot of components, you should avoid as they are either not allowed or changing, i.e. i try to avoid corporate names in server names and active directory as much as possible. Companies are often renaming themselfs these days as part of merger and aquisitions.

When working with Azure and especially Azure Landing zones, please read the guide on naming convention by Microsoft here.

For more information on DNS, check my article here and learn about using the right DNS configuration for your homelab.

Table of reserved words – Source Microsoft