Integrated Windows Authentication (IWA)
is a term associated with Microsoft products that refers to the SPNEGO, Kerberos, and NTLMSSP authentication protocols with respect to SSPI functionality introduced with Microsoft Windows 2000 and included with later Windows NT-based operating systems. The term is used more commonly for the automatically authenticated connections between Microsoft Internet Information Services, Internet Explorer, and other Active Directory aware applications.
IWA is also known by several names like HTTP Negotiate authentication, NT Authentication, NTLM Authentication, Domain authentication, Windows Integrated Authentication, Windows NT Challenge/Response authentication, or simply Windows Authentication.

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