DNS > How to Design a DNS Namespace

You can design an external namespace that is visible to Internet users and computers, and you can also design an internal namespace that is accessible only to users and computers that are within the internal network.

Organizations that require an Internet presence as well as an internal namespace must deploy both an internal and an external DNS namespace and manage each namespace separately. In this case, it is recommended that you make your internal domain a subdomain of your external domain. Using an internal domain that is a subdomain of an external domain:

• Requires you to register only one name with an Internet name authority even if you later decide to make part of your internal namespace publicly accessible.
• Ensures that all of your internal domain names are globally unique.
• Simplifies administration by enabling you to administer internal and external domains separately.
• Allows you to use a firewall between the internal and external domains to secure your DNS deployment.

You can use your internal domain as a parent for additional child domains that you create to manage divisions within your company, in cases where you are deploying an Active Directory domain for each division. Child domain names are immediately subordinate to the domain name of the parent. For example, a child domain for a manufacturing division that is added to the us.corp.contoso.com namespace might have the domain name manu.us.corp.contoso.com.