Which concept enables authentication across security domains, supporting resource access across domains?

Which concept enables authentication across security domains, supporting resource access across domains?

• A. Cross-Domain Connections
• B. Directory Services
• C. Federation of Identity (FIdM)
• D. Peering

Answer: (C)

Federation of Identity enables authentication across security domains by establishing trusted relationships so a user authenticated in one domain can access resources in another without re-authenticating. In practice, an identity provider in the user’s home domain vouches for who the user is and issues a token or assertion that a service in the target domain accepts. Standards such as SAML, OAuth, and OpenID Connect support this, making it possible to achieve single sign-on across organizations and domains.

This approach directly addresses the need to authenticate across domains and grant resource access in multiple security boundaries. The other options don’t fit the cross-domain authentication goal: Directory Services manage authentication within a single domain, Cross-Domain Connections suggests general network links rather than trust and identity sharing, and Peering refers to network connections between providers rather than identity and access management.