
Explanation:
WS-Federation
WS-Federation is the WS-Security specification that maintains a single authenticated identity across multiple dissimilar environments. WS-Federation is a specification that defines mechanisms for federated identity and access management, which allows users or devices to use a single identity or credential to access multiple or different applications, systems, or networks, without requiring to authenticate or to login separately or repeatedly for each application, system, or network. WS-Federation is based on the WS-Trust specification, which defines mechanisms for issuing, renewing, and validating security tokens, such as SAML assertions or Kerberos tickets, that can be used as credentials for federated identity and access management.
References: CISSP Official (ISC)2 Practice Tests, Chapter 4, page 122; Official (ISC)2 CISSP CBK Reference, Fifth Edition, Chapter 4, page 179