Help please

I am trying to create a DC in Azure using the template. I have filled in the required fields
AdminUsername
AdminPassword
DomainName
but when I get to the DNS Prefix whatever I put in gets an error
"code": "InvalidDomainNameLabel",
"message": "The domain name label AD_LB is invalid. It must conform to the following regular expression: ^[a-z][a-z0-9-]{1,61}[a-z0-9]$.",
I have tried example
example.example.com
example.com
.example.com
.example
I am probably being dumb but have spent over 10 hours trying different strings. Please help.

Thanks

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Sorry to hear you had a bad experience with one of the templates :worried: But, in case you're just asking a question, we're happy to help. You can also check if the question might already have been asked here https://github.com/Azure/azure-quickstart-templates/issues?utf8=%E2%9C%93&q=is%3Aissue

We've created an outline of recommended sections to fill out that will help make this Pull Request awesome!

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[Template Name goes here](Template link goes here)

### Issue Details

### Repro steps (*if necessary, delete otherwise*)
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Start with the Azure template referenced by the report, which is not linked here, and inspect how its DNS Prefix field is defined. Reproduce the deployment with a value matching the error's stated pattern, then determine whether the template or the supplied input causes the InvalidDomainNameLabel response; done means documenting or correcting that cause.

Written by the indexing model from the issue text.