What is the difference betweena single-master and a multi-master domain replication model?

Answer 1

Multi-master replication is a method of database replication which allows data to be stored by a group of computers, and updated by any member of the group.

The multi-master replication system is responsible for propagating the data modifications made by each member to the rest of the group, and resolving any conflicts that might arise between concurrent changes made by different members.

Multi-master replication can be contrasted with master-slave replication, in which a single member of the group is designated as the "master" for a given piece of data and is the only node allowed to modify that data item. Other members wishing to modify the data item must first contact the master node. Allowing only a single master makes it easier to achieve consistency among the members of the group, but is less flexible than multi-master replication

Flexible Single Master of Operation or just single master operation or operations master, is a feature of Microsoft's Active Directory (AD).

FSMOs are specialized domain controller tasks, used where standard data transfer and update methods are inadequate. AD normally relies on multiple peer DCs, each with a copy of the AD database, being synchronized by multi-master replication. The tasks which are not suited to multi-master replication, and are viable only with a single-master database, are the FSMOs.

Once per domain they only replicate to all

The Relative ID Master allocates security RIDs to DCs to assign to new AD security principals (users, groups or computer objects). It also manages objects moving between domains.

The Infrastructure Master maintains security identifiers, GUIDs, and DN for objects referenced across domains. Most commonly it updates user and group links.This is another domain-specific role and its purpose is to ensure that cross-domain object references are correctly handled. For example, if you add a user from one domain to a security group from a different domain, the Infrastructure Master makes sure this is done properly. As you can guess however, if your Active Directory deployment has only a single domain, then the Infrastructure Master role does no work at all, and even in a multi-domain environment it is rarely used except when complex user administration tasks are performed. Because of this, the hardware requirements for machines holding this role are relatively small.

The PDC Emulator operations master role processes all password changes in the domain. Failed authentication attempts due to a bad password at other domain controllers are forwarded to the PDC Emulator before rejection. This ensures that a user can immediately login following a password change from any domain controller, without having to wait several minutes for the change to be replicated. The PDC Emulator Operations Master role must be carefully sited in a location to best handle all password reset and failed-authentication forwarding traffic for the domain. The PDC emulator role holder retains the following functions:

1.Password changes performed by other DCs in the domain are replicated preferentially to the PDC emulator.

2.Authentication failures that occur at a given DC in a domain because of an incorrect password are forwarded to the PDC emulator before a bad password failure message is reported to the user.

3.Account lockout is processed on the PDC emulator.

4.backward compatibility,The PDC emulator performs all of the functionality that a Microsoft Windows NT 4.0 Server-based PDC or earlier PDC performs for Windows NT 4.0-based or earlier clients.

Once per forest

The Schema Master maintains all modifications to the schema of the forest. The schema determines the types of objects permitted in the forest and the attributes of those objects.

The Domain Naming Master tracks the names of all domains in the forest and is required to add new domains to the forest or delete existing domains from the forest. It is also responsible for group membership.

• Multi-master replication is a replication model in which any domain controller accepts and replicates directory changes to any other domain controller. Because multiple domain controllers are employed, replication continues, even if any single domain controller stops working.

• Single-master replication is a replication model in which one domain controller accepts and replicates directory changes to any other domain controller. This master domain controller is known as "Operation Master".