What is the best way to prevent an Azure administrative password from being stored in plain text when deploying through an ARM template?

Using an Azure Key Vault to store sensitive information, such as administrative passwords, is the best practice for preventing such data from being exposed in plain text when deploying through an Azure Resource Manager (ARM) template. The Azure Key Vault service is specifically designed to securely store secrets, keys, and certificates, making it an ideal solution for managing sensitive information.

When you store a password in Azure Key Vault, it is encrypted and access can be controlled through access policies. This allows you to set specific permissions for users, groups, or applications that need to retrieve the password, ensuring that only authorized entities can access sensitive data. During the deployment of the ARM template, you can reference the password stored in Key Vault rather than including it directly in the template, which mitigates the risk of accidental exposure.

In contrast, other options such as a Recovery Services vault or Azure Storage account do not specifically address the management of secrets and sensitive information in the same secure manner. Azure AD Identity Protection focuses on identity security management rather than secret management. Therefore, leveraging Azure Key Vault provides a focused and secure method to handle sensitive credentials like passwords during deployments.