The above stated certifications are described below:
MCTS: Windows Server 2008 Active Directory Configuration certification is designed for the professionals who want to work with Active Directory and Directory Services, Active Directory server roles, certificate management, and Group Policy. You need to pass 70-640: TS: Windows Server 2008 Active Directory, Configuring exam to get MCTS: Windows Server 2008 Active Directory Configuration certification.
MCTS: Windows Server 2008 Network Infrastructure Configuration certification is designed for the professionals who want to work with IP addressing and services, names resolution, file and print services, network access and remote access, and monitoring network services. You need to pass 70-642: TS: Windows Server 2008 Network Infrastructure, Configuring exam to get MCTS: Windows Server 2008 Network Infrastructure Configuration certification.
MCTS: Windows Server 2008 Applications Infrastructure Configuration certification is designed for the professionals who want to work with Windows deployment services, terminal services, Web services, and media services. You need to pass 70-643: TS: Windows Server 2008 Applications Infrastructure, Configuring exam to get MCTS: Windows Server 2008 Applications Infrastructure Configuration certification.
If you are MCSA on Windows Server 2003 and want to get MCTS: Windows Server 2008 Active Directory, Configuration and MCTS: Windows Server 2008 Network Infrastructure Configuration then you need to pass 70-648: TS: Upgrading Your MCSA on Windows Server 2003 to Windows Server 2008
OR
If you are MCSE on Windows Server 2003 and want to get MCTS: Windows Server 2008 Active Directory Configuration, MCTS: Windows Server 2008 Network Infrastructure Configuration, and MCTS: Windows Server 2008 Applications Infrastructure Configuration then you need to pass 70-649: TS: Upgrading Your MCSE on Windows Server 2003 to Windows Server 2008
