Active Directory Domain Services in Hybrid Environments

Deploy and manage AD DS domain controllers

Deploying Active Directory Domain Services (AD DS) domain controllers means installing the role on Windows Server and promoting the server to a domain controller. The promotion process either adds a new domain controller to an existing domain or creates a new domain in a new forest. In a hybrid environment, domain controllers can run on-premises, in Azure virtual machines, or both. A key decision is whether to use a single site or multiple sites, because domain controllers replicate directory data among themselves using the Active Directory replication topology. The replication behavior changes when you add Azure-based domain controllers: you must configure sites and subnets so that domain controllers in Azure replicate efficiently with on-premises controllers, often through a VPN or ExpressRoute connection. Managing domain controllers includes monitoring their health, applying updates, and possibly demoting or decommissioning them when no longer needed.

Configure and manage multi-site, multi-domain, and multi-forest environments

A multi-site environment organizes domain controllers into physical or logical sites to control replication traffic and optimize authentication. You create Active Directory sites and assign subnets to them, then define site links with a cost and replication schedule. Traffic flows between sites according to these links, and the Knowledge Consistency Checker (KCC) automatically generates the replication topology. In a multi-domain environment, the domain hierarchy within a single forest shares a common schema and configuration, but each domain has its own security boundaries. Users and resources in one domain can be trusted by another domain through transitive trusts created automatically within the forest. A multi-forest environment introduces forest trusts, which are either one-way or two-way and can be transitive or nontransitive. Managing multiple forests requires careful planning of trust relationships, name resolution across forests, and authentication flow. In Azure, you can extend an on-premises forest by adding Azure-based domains or by connecting a separate Azure-based forest with a forest trust.

Create and manage AD DS security principals

Security principals in AD DS include user accounts, computer accounts, and groups. User accounts represent people or service identities and contain attributes such as password policies, account expiration, and logon hours. Computer accounts authenticate machines to the domain and are used for resource access. Groups simplify permission management; they can be security groups (used for access control) or distribution groups (used for email lists). The group scope—domain local, global, or universal—determines where the group can be used and what members it can contain. In a hybrid environment, you often synchronize these security principals to Azure AD using Azure AD Connect, which means changes made on-premises are reflected in the cloud. Managing security principals involves creating, modifying, disabling, or deleting them, and applying policies such as password complexity or account lockout through Group Policy.

Implement and manage hybrid identities

Hybrid identity enables users to use the same credentials to access on-premises resources and cloud services like Microsoft 365. The main tool is Azure AD Connect, which synchronizes identities from on-premises AD DS to Azure AD. You choose between password hash synchronization (password hashes are synced to Azure AD), pass-through authentication (password validation happens on-premises), or federation (using Active Directory Federation Services). The synchronization process also handles group memberships, device registrations, and attribute mappings. Managing hybrid identities includes configuring synchronization rules, monitoring sync health, and handling writeback operations such as password writeback (allowing users to reset their on-premises password from the cloud). The relationship between on-premises AD DS and Azure AD is a one-way synchronization by default, but you can enable features like Exchange hybrid deployment or hybrid Azure AD join to make the experience seamless.

Manage Windows Server by using domain-based Group Policies

Group Policy in AD DS allows administrators to define and enforce settings for users and computers across the domain. A Group Policy object (GPO) contains policy settings that are linked to sites, domains, or organizational units (OUs). The settings affect security, software installation, scripts, folder redirection, and many other aspects. GPOs are processed in a specific order: local, site, domain, parent OU, child OU, with later settings overriding earlier ones unless the Enforce option is used. In a hybrid environment, Group Policy applies only to on-premises domain-joined machines; Azure AD-joined devices use Microsoft Intune or Configuration Manager instead. Managing Group Policy involves creating new GPOs, editing them with the Group Policy Management Console, linking them to the right container, and filtering which users or computers receive them using security filtering or Windows Management Instrumentation (WMI) filters. Regularly reviewing GPOs and their backup is important to avoid conflicts and unintended changes.