The server infrastructure consists of over 4,500 web servers (running Windows Server 2003, IIS 6.0, ASP.NET and .NET Framework 3.5), over 1,200 cache servers (running 64-bit Windows Server 2003), and over 500 database servers (running 64-bit Windows Server 2003 and SQL Server 2005) as well as a custom distributed file system which runs on Gentoo Linux.