Microsoft has released a public preview for their new Azure Active Directory Domain Services feature in Azure Active Directory. This feature allows you to establish virtual network domains in Azure.
Azure AD Domain Services is an entirely new concept. It’s a cloud based service which gives you a fully Windows Server Active Directory compatible set of API’s and protocols, delivered as a managed Azure service. This means as part of Azure AD you can now turn on support for all the critical directory capabilities your application and server VM’s need, including Kerberos, NTLM, Group Policy and LDAP. — Active Directory Blog
This service is targeted toward providing standard domain services for Azure hosted VMs and applications, not desktops. The service includes domain join and group policy features and works with on-premise AD via Azure AD Connect. Using Azure AD Domain Services will enable legacy application users to use the same logins as other cloud based services such as Office 365.
For more information on this new service and how to configure it, read the Active Directory team’s blog post.