Am not getting the domainNameLabel correct

Hope it's okay to post a general question here that is not really an issue, but more my lack of understanding on what is being expected. I'm following this post on the Dell site (https://community.emc.com/docs/DOC-80070) to prepare and run this template. The writer said that the value for the Domain Name Label parameter in the setup script must be used as the CN in the SSL certificate that is created. In his example he has this value as "CN=cseregistry.rack04.cloudapp.azs.mhclabs.com". So in my setup script (and in my certificate) I used the value of "csregistry.local.cloudapp.azurestack.external", as this seemed comparable for my Azure Stack SDK environment. But when I run the deploy script, the deployment fails, complaining that "The domain name label csregistry.local.cloudapp.azurestack.external is invalid. It must conform to the following regular expression:
^[a-z][a-z0-9-]{1,61}[a-z0-9]$." Obviously I am misunderstanding something. Can anyone set me straight on this?

Commencez par le script de setup et le script de déploiement référencés dans le rapport, puis comparez leur gestion de Domain Name Label avec les instructions Dell liées. Documentez la valeur attendue pour le paramètre et son lien avec le CN du certificat SSL ; l’issue est terminée lorsque l’exigence de déploiement est sans ambiguïté.

Rédigé par le modèle d'indexation à partir du texte de l'issue.