Azure Directory Domain Services for On-Premises Integration

Azure Directory Domain Services for on-premises integration is a game-changer for businesses with existing infrastructure. It allows you to manage and synchronize identities across your on-premises and Azure environments.

With Azure Directory Domain Services, you can create a managed domain in Azure that mirrors your on-premises Active Directory. This enables seamless integration and synchronization between your on-premises and cloud environments.

This integration is especially useful for businesses with multiple locations or remote workers, as it allows for centralized identity management and reduced complexity.

By using Azure Directory Domain Services, you can simplify your IT infrastructure and reduce administrative tasks, freeing up resources for more strategic initiatives.

If you're setting up Azure Directory, you have two main options: joining your on-premises forest to Azure or creating a separate forest in Azure.

You can deploy AD DS servers to Azure and join them to your on-premises forest, which allows you to use AD DS features not yet implemented by Microsoft Entra ID.

This setup provides access to the same identity information available on-premises, and you can authenticate user, service, and computer accounts both on-premises and in Azure.

You don't need to manage a separate AD forest, as the domain in Azure can belong to your on-premises forest.

However, you must deploy and manage your own AD DS servers and domain in the cloud, which can be a bit more complex.

There may also be some synchronization latency between the domain servers in the cloud and the servers running on-premises.

Here are the key benefits of joining your on-premises forest to Azure:

Alternatively, you can create a separate Active Directory forest in Azure, which is trusted by domains in your on-premises forest.

This setup allows you to implement on-premises identities and separate Azure-only identities, which can be useful for maintaining security separation.

However, authentication within Azure for on-premises identities requires extra network hops to the on-premises AD servers, which can impact performance.

You must also deploy your own AD DS servers and forest in the cloud, and establish the appropriate trust relationships between forests.

Here are the key benefits of creating a separate forest in Azure:

Ultimately, the choice between joining your on-premises forest to Azure or creating a separate forest in Azure depends on your specific needs and requirements.

You can deploy AD DS servers to Azure and create a domain in Azure that's joined to your on-premises AD forest.

This option is ideal if you need to use AD DS features not currently implemented by Microsoft Entra ID.

To use this option, you'll need to deploy and manage your own AD DS servers and domain in the cloud, which can be a bit complex.

You can also integrate your on-premises domains with Microsoft Entra ID, which provides a managed and maintained AD infrastructure in the cloud.

Microsoft Entra ID is not an extension of an on-premises directory, but rather a copy that contains the same objects and identities.

To integrate your on-premises domains with Microsoft Entra ID, you'll need to configure connectivity with your on-premises domain to keep the Microsoft Entra directory synchronized.

You can also extend AD FS to Azure to perform federated authentication and authorization for components running in Azure.

AD FS in Azure provides the ability to trust external partners for authentication and is compatible with a large set of authentication protocols.

To manage Azure AD Domain services, you can use familiar Active Directory administrative tools such as the Active Directory Administrative Center (ADAC) or AD PowerShell.

To install Remote administration tools, you'll need to log in to a domain-joined machine and add the Remote Server Administration Tools and AD DS and LDS Tools, DNS tools.

Here's a step-by-step guide to managing Azure AD Domain services:

To set up an Azure Directory Domain, you'll need to create a new directory. This can be done through the Azure portal, where you'll need to provide a domain name and a subscription plan.

Choose a suitable domain name that's easy to remember and relevant to your organization. You can also consider purchasing a custom domain name for your Azure Directory Domain.

Once you've created your directory, you can add users and groups to it. This will allow you to manage access to your Azure resources and services.

To set up a secure and efficient workflow, you'll want to consider the following key components.

The on-premises network is the foundation, including local Active Directory servers that handle authentication and authorization for components located on-premises.

Active Directory servers are hosted in the cloud, running as VMs and providing authentication for components in your Azure virtual network.

These servers are isolated in a separate subnet, protected by network security group (NSG) rules that act as a firewall against unexpected traffic sources.

Azure VPN Gateway provides a connection between the on-premises network and Azure Virtual Network, handling synchronization requests between cloud and on-premises Active Directory servers.

User-defined routes (UDRs) are used to handle routing for on-premises traffic passing to Azure.

Here are the key components of the workflow:

When determining your VM size requirements, consider the expected volume of authentication requests and match it with Azure VM sizes based on the specifications of the machines hosting AD DS on-premises.

Use the machines hosting AD DS on-premises as a starting point to determine your VM size requirements.

You should deploy at least two VMs running AD DS as domain controllers and add them to different availability zones.

Deploying in an availability set is a good alternative if different availability zones are not available in the region.

Create a separate virtual data disk for storing the database, logs, and sysvol folder for Active Directory.

Don't store these items on the same disk as the operating system to avoid potential conflicts.

Set the Host Cache Preference setting on the data disk to None to ensure compatibility with AD DS requirements.

Monitor utilization and scale up or down based on the actual load on the VMs to ensure optimal performance.

To ensure the security and reliability of your Azure Directory Domain, it's essential to take proactive measures. Deploy the VMs running AD DS into at least two availability zones to prevent data loss in case of a hardware failure.

You should also consider assigning the role of standby operations master to at least one server, and possibly more, depending on your requirements. This way, if the primary operations master's server fails, the standby operations master can take over seamlessly.

To secure your AD DS servers, prevent direct Internet connectivity by placing them in a separate subnet with an NSG as a firewall. This will block any unauthorized access attempts.

When configuring the network interface for your Active Directory Domain Services (AD DS) servers, it's essential to use a static private IP address for full DNS support. This is crucial for a seamless domain name service experience.

You should never configure a VM NIC for any AD DS server with a public IP address, as this poses significant security risks. For more information on security considerations, see the relevant section.

To ensure incoming and outgoing traffic to and from your on-premises infrastructure, you'll need to configure the Active Directory subnet Network Security Group (NSG) with specific rules. The Active Directory and Active Directory Domain Services Port Requirements document provides a detailed list of the necessary ports.

If your new domain controller VMs also serve as DNS servers, it's recommended to configure them as custom DNS servers at the virtual network level. This will improve performance and increase the availability of DNS services for your virtual network and peered networks.

Reliability is crucial for meeting your commitments to customers.

Deploying VMs running AD DS into at least two availability zones is a good practice. This ensures that your application remains accessible even in the event of a failure.

If availability zones aren't available in the region, use availability sets as a fallback option.

Assigning the role of standby operations master to at least one server can also help with failover. Having multiple servers with this role can provide even more redundancy.

AD DS servers are an attractive target for attacks, so it's essential to secure them. Prevent direct Internet connectivity by placing the AD DS servers in a separate subnet with a Network Security Group (NSG) as a firewall.

Closing all ports on the AD DS servers except those necessary for authentication, authorization, and server synchronization is a must. This will help protect against unauthorized access.

Use either BitLocker or Azure disk encryption to encrypt the disk hosting the AD DS database. This will safeguard your valuable data.

Enabling Azure DDoS Protection on any perimeter virtual network is a good practice. It provides enhanced DDoS mitigation features to defend against DDoS attacks.

Managing your Azure Directory Domain requires some special considerations. Don't shut down a domain controller VM using the Azure portal, as this can cause issues with the Active Directory repository.

Shutting down through the Azure portal resets the VM-GenerationID and invocationID, discards the current RID pool, and marks the sysvol folder as nonauthoritative. The first issue is relatively benign, but repeated resetting of the invocationID will cause minor additional bandwidth usage during replication.

RID pool exhaustion is a more serious issue, especially if the RID pool size has been configured to be larger than the default. Consider monitoring the domain for RID pool exhaustion warning events, as this can indicate a problem.

You can manage domain services using familiar Active Directory administrative tools like the Active Directory Administrative Center (ADAC) or AD PowerShell. However, you can't manage domain services via Remote Desktop connections because you don't have the necessary privileges.

To manage domain services, you need to install Remote administration tools on a domain-joined machine. This involves logging into the Domain-Joined machine, adding the Remote Server Administration Tools, and confirming the installation.