Overview
Introduction to Active Directory Replication
Active Directory (AD) replication is the process by which data changes in one
domain controller (DC) are automatically synchronized across all other domain controllers
in an Active Directory environment. This ensures consistency and reliability across the
directory service.
Replication is a core feature of Active Directory, enabling it to function as a
distributed and fault-tolerant system.
Replication Components and Processes
How Replication Works
Replication Latency
Default Replication Latency (Change Notification) = 5 minutes
When No Changes, Scheduled Replication = One Hour
Urgent Replication = Immediate Change Notification
Resolving Replication Conflicts
Attribute Value
Adding/Moving Under a Deleted Container Object or the Deletion of a Container Object
Sibling Name
Optimizing Replication
Replication Topology
Directory Partitions
Contains definitions and rules for creating and manipulating all objects and attributes
Contains information about Active Directory structure
Holds information about all domain-specific objects created in Active Directory
What Is Replication Topology?
Global Catalog and Replication of Partitions
Automatic Replication Topology Generation
Using Connection Objects
Connection Objects Are Created: Automatically or Manually
Connection Objects Are Created on Each Domain Controller
Use Active Directory Sites and Services to Manually Create, Delete, and Adjust Connection Objects
Use the Replicate Now Option to Manually Initiate Replication
Using Sites to Optimize Active Directory Replication
What Are Sites?
The First Site Is Set Up Automatically, and Is Called Default-First-Site-Name
Sites Can Consist of Zero, One, or More Subnets
Sites Are Used to Control Replication Traffic and Logon Traffic
Sites Contain Server Objects and Are Associated with IP Subnet Objects
Replication Within Sites
Occurs Between Domain Controllers in the Same Site
Assumes Fast and Highly Reliable Network Links
Does Not Compress Replication Traffic
Uses a Change Notification Mechanism
Replication Between Sites
Occurs on a Manually Defined Schedule
Is Designed to Optimize Bandwidth
One or More Replicas in Each Site Act As Bridgeheads
Replication Protocols
RPC for Replication Within and Between Sites
SMTP for Replication Between Sites
Implementing Sites to Manage Active Directory Replication
Creating Sites and Subnets
The use of universal groups to limit replication to a domain
The membership in universal groups to other groups rather than user accounts
Changes to the membership to reduce the frequency of replication
Creating and Configuring Site Links
Transport
Member sites
Cost
Schedule
Replication Interval
Creating a Site Link Bridge
Monitoring Replication Traffic
What Is Replication Monitor?
With Replication Monitor You Can:
Display the Replicating Partner
Display Each USN Value, the Number of Failed Attempts, Reason, and Flags
Poll the Server at an Administrator-Defined Interval
Monitor the Count of Failed Replication Attempts
Display Each USN Value, the Number of Failed Attempts, Reason, and Flags
Using Replication Monitor to Monitor Replication Traffic
Show Which Objects Have Not Yet Replicated
Synchronize Between Just Two Domain Controllers
Trigger the KCC into Recalculating the Replication Topology
Using Replication Monitor to Monitor Replication Traffic
Using Repadmin to Monitor Replication Traffic
Adjusting Replication
Modify the Replication Behavior by:
Creating Additional Connection Objects to:
Reduce the number of hops between domain controllers
Bypass the failed server or servers
Configuring Preferred Bridgehead Servers
Troubleshooting Active Directory Replication
Replication Does Not Finish
Replication Is Slow
Replication Increases Network Traffic
Replication Clients Are Receiving a Slow Response
KCC Was Unable to Complete the Topology
Best Practices
Place at Least One Domain Controller in Every Site
Place At Least One DNS Server in Each Site
Schedule Site Links for Times When Network Traffic Is Slow