Which of the following Protocols Is Used by Active Directory for Authentication
The Active Directory database is organized into partitions, each containing specific types of objects and following a specific replication pattern. Microsoft often calls these partitions “naming contexts.”  The `Schema` partition contains the definition of object classes and attributes within the forest. The Configuration partition contains information about the physical structure and configuration of the forest (for example, . B site topology). Both are replicated on all areas of the forest. The Domain partition contains all objects created in that domain and is replicated only in its domain. Active Directory (AD) is a directory service developed by Microsoft for Windows domain networks. It is included in most Windows Server operating systems as a set of processes and services.   Initially, Active Directory was only used for centralized domain management. However, Active Directory eventually became a generic title for a wide range of directory-based identity-related services.  Sites are physical (not logical) groupings defined by one or more IP subnets.
 AD also includes connection definitions, distinguishing between low-speed connections (e.B. WAN, VPN) and high-speed connections (e.B. LAN). Site definitions are common throughout the forest, regardless of the domain and structure of the organizational unit. Sites are used to control network traffic generated by replication and to direct clients to the nearest domain controllers (DCs). Microsoft Exchange Server 2007 uses the site topology for mail routing. Policies can also be set at the site level. Another option is to use a different directory service because non-Windows clients authenticate to it, while Windows clients authenticate to AD.
Non-Windows clients include 389 Directory Server (formerly Fedora Directory Server, FDS), ViewDS Identity Solutions – ViewDS v7.2 XML Enabled Directory, and Sun Microsystems Sun Java System Directory Server. The latter two are both capable of performing two-way synchronization with AD, allowing for “distracted” integration. Each connection can result in “costs” (for example. B, DS3, T1, ISDN, etc.), and the KCC modifies the topology of the site links accordingly. Replication can be transitive between multiple site links on site binding bridges of the same protocol if costs are low, although KCC automatically costs a lower direct site-to-site connection than transitive connections. Site-to-site replication can be configured to occur between a bridgehead server in each site, which then replicates the changes to other domain controllers within the site. Replication for Active Directory zones is automatically configured when DNS is enabled in the site-based domain. Active Directory replication uses remote procedure calls (RPC) over IP (RPC/IP). Between sites, SMTP can be used for replication, but only for changes to the schema, configuration, or partial attribute set of the GC (global catalog). SMTP cannot be used to replicate the default domain partition.  Each object represents a unique entity, whether it is a user, computer, printer, or group, and its attributes.
Some objects may contain other objects. An object is uniquely identified by name and has a set of attributes (the characteristics and information that the object represents) that are defined by a schema that also determines the types of objects that can be stored in Active Directory. Another option is to use OpenLDAP with its translucent overlay, which can extend entries into any remote LDAP server with additional attributes stored in a local database. Clients pointing to the local database see entries that contain both the remote and local attributes, while leaving the remote database completely intact. [Citation needed] Kerberos authentication is a huge improvement over previous technologies. Kerberos provides identity authentication by exchanging messages between the client, authentication server, and application server. Compared to NTLMv2, Kerberos makes it much more difficult for cybercriminals to infiltrate the network using strong cryptography and third-party ticket authorization, providing an extra layer of security. Typically, a network that uses Active Directory has multiple licensed Windows server computers.
Active Directory backup and restore is possible for a network with a single domain controller, but Microsoft recommends multiple domain controllers to provide automatic directory failover protection.  Domain controllers are ideally suited for single-use directory operations and should not run any other software or roles.  Active Directory synchronizes changes using multimaster replication.  Replication is retrieved by default, not push, which means that replicas retrieve changes from the server on which the change was made.  The Knowledge Consistency Checker (KCC) creates a site link replication topology using the sites defined to handle traffic. On-premises replication occurs frequently and automatically following a change notification, forcing peers to begin a pull replication cycle. Cross-site replication intervals are generally less frequent and do not use the default change notification, although it is configurable and may be identical to on-premises replication. The Active Directory database, the directory store, in Windows 2000 Server uses the JET Blue-based extensible storage engine (ESE98) and is limited to 16 terabytes and 2 billion objects (but only 1 billion security principals) in each domain controller`s database. .