What Is A Domain Controller And Why Would I Need It
User authentication and authorization is critical for protecting your network infrastructure. It ensures that only trustworthy and relevant users can access the network. A Windows Server domain logically groups users, PCs and other objects in a network, while a domain controller authenticates access requests to the domains resources. It also stores information about user accounts and devices, and it enforces security policies.
Learn the important role of a domain controller within a network infrastructure, and set it up with fault tolerance.
Create An Azure Virtual Network
In the Azure classic portal, click New> Network Services> Virtual Network> Custom Create and use the following values to complete the wizard.
|On this wizard page|
Name: Type a name for the virtual network, such as WestUSVNet.
Region: Choose the closest region.
|DNS and VPN connectivity||
DNS Servers: Specify the name and IP address of one or more on-premises DNS servers.
Connectivity: Select Configure a site-to-site VPN.
Local network: Specify a new local network.
If you are using ExpressRoute instead of a VPN, see Configure an ExpressRoute Connection through an Exchange Provider.
Name: Type a name for the on-premises network.
VPN Device IP address: Specify the public IP address of the device that will connect to the virtual network. The VPN device cannot be located behind a NAT.
Address: Specify the address ranges for your on-premises network .
|Virtual network address spaces||
Address Space: Specify the IP address range for VMs that you want to run in the Azure virtual network . This address range cannot overlap with the address ranges of the on-premises network.
Subnets: Specify a name and address for a subnet for the application servers and for the DCs .
Click add gateway subnet.
Next, you’ll configure the virtual network gateway to create a secure site-to-site VPN connection. See Configure a Virtual Network Gateway for the instructions.
So Can Azure Ad Fully Replace The On
The short answer is no. Not yet anyway. Azure AD is not actually a cloud replica of the original.
Replace is the key here â it is possible to replace on-premises AD with Azure AD as long as you donât have legacy applications that require a local domain controller. Itâs also possible to replace some Group Policy functionality with Microsoft InTune. In many cases, when a company goes through a divestment , the new environments can be Azure AD only as they can setup as greenfield and donât need to bring forward the on-premise infrastructure. There are also scenarios where itâs desirable to move away from on-premise infrastructure and Microsoft 365 and Azure AD allow you to do that.
Until you can go 100% cloud, your best bet is to use the two solutions together to handle access-management for both cloud and on-premise applications.
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Install Ad Ds On Azure Vms
Sign in to a VM and verify that you have connectivity across the site-to-site VPN or ExpressRoute connection to resources on your on-premises network. Then install AD DS on the Azure VMs. You can use same process that you use to install an additional DC on your on-premises network . As you install AD DS, make sure you specify the new volume for the location of the AD database, logs and SYSVOL. If you need a refresher on AD DS installation, see Install Active Directory Domain Services or Install a Replica Windows Server 2012 Domain Controller in an Existing Domain .
How Do I Install Active Directory Domain Services
You dont install AD DS per se. Rather, it is one of the server roles included in the Microsoft Windows Server operating system. When you install Windows Server on a machine, you need to specify what role or roles that server will play: file server, web server, DNS server and so on .
Figure 1. When you install Windows Server on a machine, you need to specify what roles that server will play.
As you can see in the figure, there are a variety of other roles you can assign to a server, including:
- Active Directory Certificate Services Enables the DC to serve digital certificates, signatures and public key cryptography
- Active Directory Federation Services Provides single sign-on so users dont have to keep providing the same credentials
- Active Directory Lightweight Directory Services Enables use of LDAP for communicating with other directory services servers, such as any Linux computers in your network
- Active Directory Rights Management Services Helps protect information through persistent usage policies that remain with the content no matter where it is moved
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Ad Vs Azure Ad Should You Use One The Other Or Both
If you have a traditional on-premise set up with AD and also want to use Azure AD to manage access to cloud applications then you can happily use both.
If you are using Office 365 then your users will have a username and password for that , as well as a username and password for their network logon . These two sets of credentials are un-related. This is fine, and just means that if you have a password change policy that users will have to do this twice.
Or you can synchronise AD with Azure ADso that the users only have one set of credentials which they use for both their network logon, and access to O365. You use Azure AD Connect to do this, it is a small free piece of Microsoft software that you install on a server to perform the synchronisation.
If you are a new business or one that is looking to transition away from having any traditional on-premise infrastructure and using purely cloud based applications, then you can operate purely using Azure AD.
In this case, although you will have all your applications in the cloud, you will of course still have physical devices PCs and smart phones that your team will use to access and work with these cloud applications.
What Is Active Directory Domain Services Is It Different From Active Directory
Active Directory Domain Services and Active Directory are the same thing: a database with critical information like all the various users and computers you have, and associated services that control much of the activity that goes on in your IT environment.
As one Redmond Magazine article puts it, An Active Directory environment means that you must have at least one server with the Active Directory Domain Services installed.
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Why Configure A Dc In Azure Iaas
In an Azure AD Passthrough Authentication scenario, the on premises Domain controller is a single point of failure for each O365 authentication request. So is the Azure AD Connect server. If either service is DOA, users wont be able to sign in to Azure AD or Office 365.
Passthrough authentications flow goes from Azure AD > Internet > Azure AD Connect Pass-through Auth Agent > AD Domain Controller, then backwards. Any one of those components can be a single point of failure, but all can be setup for resiliency with high availability and/or DR.
To guard against an outage of the entire data center or its Internet connection, put a Domain Controller in Azure. This way if anything happened on-premises, the Azure and Office 365 environments would still be fully functional .
Accept Ad Ds Limitations
Sometimes directives are mandated despite the repercussions. If thats the case, you will have to acceptthe limitations. That may be fine as a stop-gap for a legacy application butnot as a solution for managing enterprise clients. If Azure AD DS is used for managing clients,consider how the organization will migrate to Windows AD when the limitations makethe service no longer viable.
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Can Azure Active Directory Replace On
Active Directory is Microsoftâs on-premises solution for managing network access, including user logins, profiles, hierarchies, and devices. Itâs been an industry standard for over twenty years. Most organizations currently using Microsoft Office are also using Active Directory.
Azure â the companyâs SaaS product for building and managing Microsoft solutions in the cloud â was released in 2010, with Azure AD being the cloud counterpart to Active Directory. Since then, IT peeps have been wondering if Azure AD will eventually render the OG AD obsolete.
Is Azure AD an exact cloud replica of Microsoft Active Directory? Or is it something different altogether? Letâs take a look at both solutions and see if Azure AD is actually capable of replacing the on-premise version.
Why Should I Have A Secondary Domain Controller
A domain controller authenticates and authorizes users, which is a primary security function in a network infrastructure. It has all the keys to the realm of your Windows Server domain. Now, if your domain controller goes down, there will be no way for your users to authenticate themselves and access any of the domains resources. All applications, services and even business-critical systems that require Active Directory authentication will be inaccessible. Automatic designation of Internet Protocol addresses will fail, forcing system administrators to revert to manual assignments.
You may even have to rebuild your entire server from scratch, which could take days and even weeks if your company does not have an established backup protocol. This is why resilience is so important for ensuring business continuity and minimal or no downtime. Investing in a secondary domain controller can reduce downtime considerably in the event of domain controller failure. While your IT team works to restore the failed domain controller, a secondary domain controller will ensure that your users are able to access important domain resources and that business-critical systems and services keep running until everything goes back to normal.
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Why Is A Domain Controller Important
Domain controllers control all domain access, blocking unauthorized access to domain networks while allowing users access to all authorized directory services.
The domain controller mediates all access to the network, so it is important to protect it with additional security mechanisms such as:
- security protocols and encryption to protect stored data and data in flight
- restricted use of insecure protocols, such as remote desktop protocol, on controllers
- deployment in a physically restricted location for security
- expedited patch and configuration management
- blocking internet access for domain controllers
Domain controllers control all access to computing resources in an organization, so they must be designed to resist attacks and to continue to function under adverse conditions.
Active Directory Sites & Services
Its important to create a new site with a corresponding subnet that whill contain your new domain controller. Clients will try to contact the domain controller in their subnet first so a misconfiguration can cause slow logons or other problems. If your on-premises subnet isnt visible here you should create this one too!
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Windows Server 2019 Benefits Caveats
Although Windows Server 2019 turns 2 years old in October, many IT admins still have reservations about moving their Active Directory setup to the new server OS. There is a prevailing attitude that older OSes have been battle-tested and, therefore, should be more reliable. In addition, with older systems, another customer has likely experienced a particular issue you might run up against, so a quick Google search could find a remedy.
While you won’t encounter any Active Directory forest and domain-functional level changes from Windows Server 2016 to Windows Server 2019, a migration to the new operating system comes with overall security improvements and added resiliency to the Hyper-V platform. For example, Microsoft introduced a new feature in virtualized environments that enables administrators to move failover clusters from one domain to another during consolidation efforts. This option didn’t exist prior to Windows Server 2019 and required administrators to remove and rebuild the cluster on the new domain from scratch.
Organizations that use on-premises Exchange should avoid migrating to Windows Server 2019 Active Directory unless they have Exchange 2016 or newer. While this configuration might work with earlier versions of Exchange, it isn’t supported by Microsoft.
This video tutorial by contributor Brien Posey explains how to set up the Windows Server 2019 domain controller. The transcript of these instructions follows.
What Are The Main Functions Of A Domain Controller
Domain controllers restrict access to domain resources by authenticating user identity through login credentials, and by preventing unauthorized access to those resources.
Domain controllers apply security policies to requests for access to domain resources. For example, in a Windows AD domain, the domain controller draws authentication information for user accounts from AD.
A domain controller can operate as a single system, but they are usually implemented in clusters for improved reliability and availability. For domain controllers running under Windows AD, each cluster comprises a primary domain controller and one or more backup domain controllers . In Unix and Linux environments replica domain controllers copy authentication databases from the primary domain controller.
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Aadds Is Not Active Directory As You Know It Aadds:
- Does not support replication.
- Cannot set up as a trusted domain to other domains
- No Domain/Enterprise admin privilege
- Schema extensions are not supported
- AD domain/forest trusts not supported
- LDAP write not supported.
- Certificate/Smartcard based authentication is not supported by Azure AD Domain Services.
- Does not support managed service accounts
AAD DS is great for virtual machines hosted in Azure, simple to set up and works well with your Azure AD. AAD DS does NOT replace a proper domain controller and does not work with managing users and computers like with Windows Server Active Directory. AAD DS works great if you plan on a cloud-only strategy with limited users, and not GPOs.
To date, we mostly implement Hybrid Azure Active Directory by moving our clients existing on-premise domain controller into a virtual machine hosted on Azure, using an availability set for fail-over and redundancy capability, install AD Connect to synchronize with Azure AD and create a VPN connection between their office and the Azure datacenter. With this option, you can leverage the power of Azure while making sure your legacy application will still run.
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