Active Directory Domain Service (AD DS) is widely used directory service and foundation of Windows domain network in organizations. It provides essential features such as centralized management, directory services, authentication, and authorization. Given its critical role within an organization, maintaining the health, security, and periodic upgrades of AD DS is paramount. Any disruption or compromise can result in significant business and financial losses.

In this blog, we will explore the industry-wide best practices for managing the various aspects of Active Directory, including maintaining its health, ensuring its security, optimizing its performance, and planning for periodic upgrades

1. Active Directory Health

Ensuring the well-being of your Active Directory environment requires consistent oversight and proactive administration. To achieve this, it's important to concentrate on several critical areas, including:

• Logs Monitoring: Regularly review security logs and alerts to detect any unusual activities or potential security breaches. Implementing tools like Security Information and Event Management (SIEM) can enhance your monitoring capabilities.
• Monitoring and Maintenance: Regularly monitor the health and performance of your AD sites and replication topology using tools like repadmin and dcdiag to identify and troubleshoot any replication problems promptly.
• Updates and Patching: Ensure that your Domain Controllers are always running the latest version of their Operating System. Additionally, implement a robust patch management strategy to guarantee that all Domain Controllers receive regular and timely updates to maintain security and performance across your network.
• AD Database: Regularly verify the integrity of the Active Directory database (NTDS.dit). Utilize tools such as ntdsutil to conduct essential maintenance tasks, including defragmentation and integrity checks, ensuring the database remains healthy and efficient.
• DNS Health: Active Directory is highly dependent on DNS, so it is essential to keep DNS healthy. Regularly check for DNS errors. Configure DNS Scavenging to automatically cleanup stale dynamically registered DNS records
• Active Directory Backup: Ensuring regular and reliable backups of your Active Directory (AD) is essential for maintaining the integrity and availability of your directory services. Here are some key recommendations:
  • Daily Backups: Ensure that at least one domain controller in each domain is backed up daily, especially those holding FSMO (Flexible Single Master Operation) roles. Use the Windows Backup tool to take System State backups, even if you are performing full VM backups.
  • Tombstone Lifetime Compliance: Back up AD frequently enough to ensure the backup age is never older than the tombstone lifetime (TSL), which is typically 180 days. Backups older than the tombstone lifetime are ineffective.
  • Disaster Recovery Plan: Integrate your AD backup into your disaster recovery plan. Provide clear instructions on how to restore your domain controllers in the event of corruption, compromise, or disaster, including accessing Directory Services Restore Mode (DSRM) when needed.

2. Active Directory Performance

• System Performance Monitoring: Regularly track the performance metrics of Domain Controllers (DC) for CPU, Memory, Disk, and Network utilization. This helps in identifying and resolving potential bottlenecks before they impact the users.
• Hardware Sizing: While a Domain Controller (DC) can technically operate on the minimum hardware required by the Operating System, this setup may result in performance issues within a production environment of substantial size. To ensure a reliable and efficient Active Directory environment, it is advisable to exceed these minimum hardware requirements. Domain Controller sizing is complex and influenced by various factors; however, the following hardware specifications are recommended for an environment supporting up to 2,000 users/devices:
  • Minimum of 2 Domain Controllers to ensure optimal performance and redundancy.
  • 4 CPU Cores to manage the Operating System, Active Directory operations, and additional software such as antivirus and monitoring agents. Aim for a baseline target of 40% processor utilization during peak periods.
  • 16 GB RAM to support the Operating System, Active Directory database, and other necessary software.
  • SSD Storage with two partitions: 100 GB for the Operating System and 150 GB for the Active Directory database, allowing for defragmentation and future growth.
  • 1 Gbps network connection to handle network traffic efficiently.
• AD Site Topology: Designing an effective Active Directory (AD) site topology is essential for optimizing performance and ensuring efficient replication and client query routing. Here are some key recommendations for AD sites:
  • Understand Your Network and Create Sites: Thoroughly understand your physical network structure, including subnets and network links, and create sites that correspond to your physical locations or network segments.
  • Domain Controller Placement and Redundancy: Place domain controllers in each site to ensure local authentication and reduce WAN traffic, ensuring redundancy by having at least two domain controllers per site.
  • Define Subnets and Configure Site Links: Define subnets within each site to accurately reflect IP address ranges and use site links to define replication paths, configuring site link costs to prioritize faster, more reliable links.
  • Replication Scheduling and Site Link Bridges: Schedule replication during offpeak hours for sites with slower links and use site link bridges to enable transitive replication between non-directly connected sites, reducing latency and improving efficiency.
  • Client Affinity and Resource Location: Configure sites to ensure client computers locate the nearest domain controllers and resources, such as DFS servers, to reduce network traffic over slow WAN links and improve logon and resource access times.
  • Site Link Cost: Adjust site link costs and replication schedules as needed to optimize performance and accommodate network changes.
• FRS to DFSR Migration: File Replication Service (FRS) is an older technology for replicating SYSVOL contents between domain controllers, but it has limitations in performance and scalability. Distributed File System Replication (DFSR) replaces FRS, offering improved performance, reliability, scalability, and bandwidth optimization. Migrating to DFSR also provides better management tools for easier monitoring and control of replication processes.
• AD Functional Level: Active Directory (AD) functional levels determine the features and capabilities available within your AD environment. They also dictate which Windows Server operating systems can be used on domain controllers within the domain or forest. It is advisable to maintain your AD environments at the latest forest and domain functional levels to leverage the most current features and security enhancements.
• Forest and Domain trust review: It is recommended to regularly review forest and domain trusts and remove those that are no longer needed. This helps ensure that only essential trust relationships are maintained, reducing potential security risks.

3. Active Directory Security

Security is paramount in any AD environment. Here are some best practices to enhance the security of your Active Directory:

• Platform and Network Security: Ensuring the security of the network and platform hosting your Domain Controllers (DCs) is paramount for maintaining a secure Active Directory (AD) environment. Here are comprehensive recommendations to enhance network and platform security:
  • Physically secure domain controllers to prevent unauthorized access.
  • Limit administrative access to domain controllers and use dedicated admin workstations for administrative tasks.
  • Use firewalls and network segmentation to protect domain controllers and other critical infrastructure.
  • Implement secure communication protocols, such as IPsec, to encrypt network traffic
  • If domain controllers are hosted in the cloud, secure cloud access by implementing strong authentication and access controls.
  • Ensure no public IP addresses are configured on domain controllers to prevent unauthorized access.
  • Use virtual private networks (VPNs) and private endpoints to secure communication between on-premises and cloud environments.
• Controllers Security:
  • Disable unwanted services:Disabling unnecessary services on your Domain Controllers (DCs) can significantly enhance security by reducing the attack surface. Here are some services that are generally recommended to disable on a domain controller:
    • Bluetooth Support Service
    • Fax Service
    • Remote Registry
    • Windows Error Reporting Service
    • Windows Media Player Network Sharing Service
    • Print Spooler
    • Program Compatibility Assistant (PCA)
    • Windows Push Notification Service (WNS)
    • Downloaded Maps Manager
    • Connected Devices Platform
    • Retail Demo Service
    • Windows Search
    • Xbox Live Auth Manag
  • Antivirus and Anti-malware: Install and maintain up-to-date antivirus and antimalware software on all domain controllers and regularly scan for and remove any detected threats.
  • Least Privilege Principle: It is essential to follow the principle of least privilege by granting users only the minimum level of access necessary for their roles and regularly reviewing and adjusting permissions to ensure they remain appropriate. Adhering to this principle helps minimize security risks and potential vulnerabilities. The following groups should have limited membership:
    • Enterprise Admins
    • Schema Admins
    • Domain Admins
    • Account Operators (if present)
    • Server Operators (if present)
    • Print Operators (if present)
    • DHCP Administrators
    • DNSAdmins
  • Secure Administrative Workstations (SAWs): Use dedicated, hardened workstations for administrative tasks to reduce the risk of credential theft.
  • Group Policy Management: Regularly review and update Group Policies to ensure they align with your security policies. Use tools like Group Policy Management Console (GPMC) to manage and audit Group Policies.
  • Regular Audits: Conduct regular security audits to identify and remediate vulnerabilities. Use tools like Microsoft Advanced Threat Analytics (ATA) to detect suspicious activities.
• OU Accidental deletion: To prevent accidental deletion of Organizational Units (OUs) in Active Directory, you can enable the "Protect object from accidental deletion" feature. When creating a new OU, ensure the "Protect object from accidental deletion" option is checked. This setting helps prevent accidental deletions by requiring additional steps to remove the protection
• AD Recycle Bin: Active Directory Recycle Bin is a greate feature that allows you to recover accidentally deleted objects, such as users, groups, and OUs, without needing to restore from backup.
• Disable SMB v1: For Active Directory (AD) security, it is highly recommended to disable SMBv1. This legacy protocol is prone to numerous vulnerabilities, making it an easy target for attackers, as evidenced by the WannaCry ransomware incident. Disabling SMBv1 mitigates risks such as downgrade attacks and man-in-the-middle attacks. Upgrading to modern SMB versions, like SMB 3.0 and above, provides enhanced security features, including encryption and improved message signing, which are essential for a secure AD environment.
• Active Directory Management: Active Directory administrators should use separate accounts for performing privileged tasks and should not use these privileged accounts for their day-to-day activities. They should avoid browsing the internet with these accounts. Additionally, administrators should not log on to compromised workstations or member servers with privileged accounts. This approach helps minimize security risks and protects sensitive administrative credentials
• Stale objects: Regularly identify and clean up stale objects to maintain a secure and efficient environment. Define criteria for stale objects based on your organization's policies, typically considering inactivity thresholds of 30, 60, or 90 days.
• Disable internet on DCs: Block internet browsing on all Domain Controllers. This can be achieved by configuring an incorrect proxy setting on Domain Controllers via Group Policy. This measure helps enhance security by preventing unauthorized internet access from critical infrastructure
• krbtgt account password reset: It is highly recommended to reset the krbtgt account password regularly, ideally every 6 to 12 months. Since the krbtgt account maintains two passwords, it is advisable to reset the password twice, with an interval of 12-24 hours between resets.
  Note: Resetting the krbtgt account password must be done carefully. Before proceeding, ensure that all Domain Controllers are powered on, Active Directory is healthy, and replication is functioning properly.
• Service Account: Ensuring the security of service accounts is vital for protecting the integrity and confidentiality of your systems. Here are some best practices to keep your service accounts secure:
  • Use Managed Service Accounts (MSAs) over traditional service accounts due to several advantages, such as automatic password management, simplified SPN management, enhanced security, and reduced administrative overhead.
  • Assign only necessary permissions to service accounts to reduce the risk of misuse
  • Do not place service accounts in built-in privileged groups like Domain Admins
  • Ensure service accounts have strong, complex passwords and implement policies to ensure passwords expire and are changed regularly
  • Use a clear and consistent naming convention for service accounts to easily identify them
  • Regularly audit service accounts to ensure they are being used appropriately and have not been compromised
  • Enable logging to track the activities of service accounts and detect any unusual behavior
  • Use the "Log On To" feature to restrict service accounts to specific computers where they are needed

4. Active Directory Upgrades

Upgrading Active Directory is a critical task that requires careful planning and execution. Here are some steps to ensure a smooth upgrade process:

• Preparation and Planning: Clearly outline the goals of the upgrade or migration, such as consolidating domains, improving security, or upgrading to a newer version of Windows Server. Define a high-level project plan that includes timelines, milestones, and resource allocation.
• Current Environment Assessment: Document the existing AD infrastructure, including domain controllers, sites, Organizational Units (OUs), Group Policies, and trust relationships. Evaluate the health of your current AD environment to ensure there are no replication issues, DNS problems, or other errors.
• Compatibility and Requirements: Verify that the current hardware and software are compatible with the new AD version. Check if the current AD schema and functional levels meet the requirements for the upgrade.
• Risk Assessment and Mitigation: Conduct a risk assessment to identify potential issues that could arise during the upgrade.
• Dependency Analysis: Identify applications and services that depend on AD and ensure they are compatible with the new version. Map out interdependencies within your AD environment to understand the impact of the upgrade.
• Backup and Recovery: Review your AD backup solution and recovery procedures. Periodically test recovery plans to ensure they work as expected.
• Testing and Validation: Set up a test environment that mirrors your production environment to validate the upgrade process.

What Mismo Systems Offer:

At Mismo Systems, we offer comprehensive services to ensure your Active Directory (AD) environment is robust, secure, and up-to-date. Our offerings include:

• Active Directory Health and Performance Review: We thoroughly assess your AD infrastructure to identify performance bottlenecks and potential issues, ensuring optimal operation and reliability.
• Active Directory Security Review: Our experts evaluate your AD security posture, identifying vulnerabilities and providing actionable recommendations to enhance your security measures.
• Active Directory Upgrade and Migration Review: We assist in planning and executing upgrades or migrations, ensuring a seamless transition with minimal disruption. Our service includes a detailed assessment of your current environment, identification of gaps, and a comprehensive roadmap to address these gaps effectively.

By leveraging our expertise, you can ensure your AD environment is well-maintained, secure, and capable of supporting your organizational needs. Let us help you achieve a resilient and efficient AD infrastructure.