Windows Server 2003 is the sixth version of Windows Server operating system produced by Microsoft. It is part of the Windows NT family of operating systems and was released to manufacturing on March 28, 2003 and generally available on April 24, 2003. Windows Server 2003 is the successor to the Server editions of Windows 2000 and the predecessor to Windows Server 2008. An updated version, Windows Server 2003 R2, was released to manufacturing on December 6, 2005. Windows Server 2003 is based on the consumer operating system, Windows XP.
Windows Server 2003 is the follow-up to Windows 2000 Server, incorporating compatibility and other features from Windows XP. Unlike Windows 2000, Windows Server 2003's default installation has none of the server components enabled, to reduce the attack surface of new machines. Windows Server 2003 includes compatibility modes to allow older applications to run with greater stability. It was made more compatible with Windows NT 4.0 domain-based networking. Windows Server 2003 brought in enhanced Active Directory compatibility and better deployment support to ease the transition from Windows NT 4.0 to Windows Server 2003 and Windows XP Professional.
Internet Information Services (IIS) has been upgraded to v6.0.There have also been significant improvements to Message Queuing and to Active Directory, such as the ability to deactivate classes from the schema, or to run multiple instances of the directory server (ADAM). There was also a notable change in the ability to create a rescue disk, which was removed in favor of Automated System Recovery (ASR).Other Improvements to Group Policy handling and administration have also been made. For the first time in the history of Windows Server, a backup system to restore lost files has been created together with improved disk management, including the ability to back up from shadows of files, allowing the backup of open files.Another important area where improvements have been made are the scripting and command line tools, with the improvements being part of Microsoft's initiative to bring a complete command shell to the next version of Windows. Other notable new features include support for a hardware-based \"watchdog timer\", which can restart the server if the operating system does not respond within a certain amount of time. On this version of Windows Server the Themes service is disabled by default, defaulting to the appearance of previous Windows versions (such as Windows 2000).
Windows Server 2003 comes in a number of editions, each targeted towards a particular size and type of business. In general, all variants of Windows Server 2003 have the ability to share files and printers, act as an application server, host message queues, provide email services, authenticate users, act as an X.509 certificate server, provide LDAP directory services, serve streaming media, and to perform other server-oriented functions.
Windows Server 2003 Web is meant for building and hosting Web applications, Web pages, and XML web services. It is designed to be used primarily as an IIS web server and provides a platform for developing and deploying XML Web services and applications that use ASP.NET technology. Domain controller and Terminal Services functionality are not included on Web Edition. However, Remote Desktop for Administration is available. Only 10 concurrent file-sharing connections are allowed at any moment. It is not possible to install Microsoft SQL Server and Microsoft Exchange software in this edition without installing Service Pack 1. Despite supporting XML Web services and ASP.NET, UDDI cannot be deployed on Windows Server 2003 Web. The .NET Framework version 2.0 is not included with Windows Server 2003 Web, but can be installed as a separate update from Windows Update.
Windows Server 2003 Web supports a maximum of 2 physical processors and a maximum of 2 GB of RAM. It is the only edition of Windows Server 2003 that does not require any client access license (CAL) when used as the internet facing server front-end for Internet Information Services and Windows Server Update Services. When using it for storage or as a back-end with another remote server as the front-end, CALs may still be required.[clarification needed]
Windows Server 2003 Enterprise is aimed towards medium to large businesses. It is a full-function server operating system that supports up to 8 physical processors and provides enterprise-class features such as eight-node clustering using Microsoft Cluster Server (MSCS) software and support for up to 64 GB of RAM through PAE. Enterprise Edition also comes in specialized variants for the x64 and Itanium architectures. With Service Pack 2 installed, the x64 and Itanium variants are capable of addressing up to 1 TB and 2 TB of RAM, respectively. This edition also supports Non-Uniform Memory Access (NUMA). It also provides the ability to hot-add supported hardware. Windows Server 2003 Enterprise is also the required edition to issue custom certificate templates.
The Datacenter edition, like the Enterprise edition, supports 8-node clustering. Clustering increases availability and fault tolerance of server installations by distributing and replicating the service among many servers. This edition supports clustering with each cluster having its own dedicated storage, or with all cluster nodes connected to a common SAN.
Windows Storage Server 2003, a part of the Windows Server 2003 series, is a specialized server operating system for network-attached storage (NAS). Launched in 2003 at Storage Decisions in Chicago, it is optimized for use in file and print sharing and also in storage area network (SAN) scenarios. It is only available through Original equipment manufacturers (OEMs). Unlike other Windows Server 2003 editions that provide file and printer sharing functionality, Windows Storage Server 2003 does not require any CAL.
Windows Storage Server 2003 NAS equipment can be headless, which means that they are without any monitors, keyboards or mice, and are administered remotely. Such devices are plugged into any existing IP network and the storage capacity is available to all users. Windows Storage Server 2003 can use RAID arrays to provide data redundancy, fault-tolerance and high performance. Multiple such NAS servers can be clustered to appear as a single device, which allows responsibility for serving clients to be shared in such a way that if one server fails then other servers can take over (often termed a failover) which also improves fault-tolerance.
Windows Storage Server 2003 led to a second release named Windows Storage Server 2003 R2. This release adds file-server performance optimization, Single Instance Storage (SIS), and index-based search. Single instance storage (SIS) scans storage volumes for duplicate files, and moves the duplicate files to the common SIS store. The file on the volume is replaced with a link to the file. This substitution reduces the amount of storage space required, by as much as 70%.
Windows Storage Server 2003 R2 provides an index-based, full-text search based on the indexing engine already built into Windows server. The updated search engine speeds up indexed searches on network shares. This edition also provides filters for searching many standard file formats, such as ZIP archives, AutoCAD models, XML documents, MP3 audio files, PDF documents, and all Microsoft Office file formats.
Windows Storage Server 2003 R2 includes built in support for Windows SharePoint Services and Microsoft SharePoint Portal Server, and adds a Storage Management snap-in for the Microsoft Management Console. It can be used to manage storage volumes centrally, including DFS shares, on servers running Windows Storage Server R2.
Windows Storage Server 2003 can be promoted to function as a domain controller; however, this edition is not licensed to run directory services. It can be joined to an existing domain as a member server.
The Standard edition of SBS includes Microsoft Remote Web Workplace, Windows SharePoint Services, Microsoft Exchange Server, Fax Server, Active Directory, a basic firewall, DHCP server and network address translation capabilities. The Premium edition of SBS adds Microsoft SQL Server 2000 and Microsoft ISA Server 2004.
Windows Server 2003 for Embedded Systems replaced \"Windows 2000 Server for Embedded Systems\". Intended use was for building firewall, VPN caching servers and similar appliances. Variants were available with \"Server Appliance Software\" and with \"Microsoft Internet Security and Acceleration Server\" 
Windows Server 2003 R2 is an updated release of Windows Server 2003, which contains a copy of Windows Server 2003 SP1 on one CD and a host of optionally installed new features on another disc, similar to Microsoft Plus! for Windows 95. It was released to manufacturing on December 6, 2005, for IA-32 and x64 platforms, but not for IA-64. It was succeeded by Windows Server 2008.
On September 23, 2020, the Windows XP Service Pack 1 and Windows Server 2003 source code was leaked onto the imageboard 4chan by an unknown user. Anonymous users from managed to compile the Windows Server 2003 source code, as well as a Twitter user who posted videos of the process on YouTube proving that the code was genuine, but was removed from the platform on copyright grounds by Microsoft. The leak was incomplete as it was missing the Winlogon source code and some other components. The original leak itself was spread using magnet links and tor