Active Directory Domain Services Command Reference Part - 1

1. Adprep

Extends the Active Directory® schema and updates permissions as necessary to prepare a forest and domain for a domain controller that runs the Windows Server® 2008 operating system.
Adprep.exe is a command-line tool that is available on the Windows Server 2008 installation disc in the \sources\adprep folder, and it is available on the Windows Server 2008 R2 installation disk in the \support\adprep folder. You must run adprep from an elevated command prompt. To open an elevated command prompt, click Start, right-click Command Prompt, and then click Run as administrator.
In Windows Server 2008 R2, Adprep is available in a 32-bit version and a 64-bit version. The 64-bit version runs by default. If you need to run Adprep on a 32-bit computer, run the 32-bit version (Adprep32.exe).
Syntax:
adprep {/forestprep | /domainprep | /domainprep /gpprep | /rodcprep | /wssg | /silent }

/forestprep - Prepares a forest for the introduction of a domain controller that runs Windows Server 2008. You run this command only once in the forest. You must run this command on the domain controller that holds the schema operations master role (also known as flexible single master operations or FSMO) for the forest.

/domainprep - Prepares a domain for the introduction of a domain controller that runs Windows Server 2008. You run this command after the forestprep command finishes and after the changes replicate to all the domain controllers in the forest.
Run this command in each domain where you plan to add a domain controller that runs Windows Server 2008. You must run this command on the domain controller that holds the infrastructure operations master role for the domain. You must be a member of the Domain Admins group to run this command.
/rodcprep - Updates permissions on application directory partitions to enable replication of the partitions to read-only domain controllers (RODCs). This operation runs remotely; it contacts the infrastructure master in each domain to update the permissions. You need to run this command only once in the forest. However, you can rerun this command any time if it fails to complete successfully because an infrastructure master is not available. You can run this command on any computer in the forest. You must be a member of the Enterprise Admins group to run this command.

Example :

adprep /forestprep

adprep /domainprep

adprep /rodcprep

 

2. Dcdiag

Analyzes the state of domain controllers in a forest or enterprise and reports any problems to help in troubleshooting.
As an end-user reporting program, dcdiag is a command-line tool that encapsulates detailed knowledge of how to identify abnormal behavior in the system. Dcdiag displays command output at the command prompt.
Dcdiag consists of a framework for executing tests and a series of tests to verify different functional areas of the system. This framework selects which domain controllers are tested according to scope directives from the user, such as enterprise, site, or single server.
Dcdiag is built into Windows Server 2008 R2 and Windows Server 2008. It is available if you have the Active Directory Domain Services (AD DS) or Active Directory Lightweight Directory Services (AD LDS) server role installed. It is also available if you install the Active Directory Domain Services Tools that are part of the Remote Server Administration Tools (RSAT).

Syntax : 
dcdiag [/s:<DomainController>] [/n:<NamingContext>] [/u:<Domain>\<UserName> /p:{* | <Password> | ""}] [{/a | /e}] [{/q | /v}] [/i] [/f:<LogFile>] [/c [/skip:<Test>]] [/test:<Test>] [/fix] [{/h | /?}] [/ReplSource:<SourceDomainController>]
Options, /s:<DomainController>--> Specifies the name of the server to run the command against. If this parameter is not specified, the tests are run against the local domain controller. This parameter is ignored for DcPromo and RegisterInDns tests, which can be run locally only.
/n:<NamingContext>-->Uses NamingContext as the naming context to test. You can specify domains in NetBIOS, Domain Name System (DNS), or distinguished name format.
/u:<Domain>\<UserName> /p:{* | <Password> | ""}-->Uses Domain\UserName. Dcdiag uses the current credentials of the user (or process) that is logged on. If alternate credentials are needed
Ref : http://technet.microsoft.com/en-us/library/cc770340(v=ws.10).aspx