@Anil Dr bheemaiah I understand you are having trouble with completing a purchase of a custom domain.
I wanted to verify for you that yes, you will need a credit card on file. A 3rd party is the provider for the custom domains. In Azure, any services that are provided by a 3rd party require a credit card as they typically cannot use credits or free trial money. For further information on the prerequisite, please see here.
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