Which authentication mechanism allows a user to log in once and access multiple systems?

Which authentication mechanism allows a user to log in once and access multiple systems?

• A. Federated Identity
• B. Single sign-on
• C. Two-factor authentication
• D. Password reuse

Answer: (B)

Single sign-on lets you authenticate once to a central identity provider and then access multiple connected systems without re-entering credentials. After you log in, the identity provider issues a token or assertion that each system trusts, so you can move between applications like email, intranet, or CRM without separate logins. This streamlines workflow and reduces password fatigue, which is why it’s the best fit for logging in once to access many services. Federated identity is about trust and sharing identity across domains, which enables SSO across organizations, but the mechanism described is the single sign-on capability itself. Two-factor authentication adds an extra verification step, not multi-system access after a single login. Password reuse describes using the same password across services, which does not provide the seamless access across systems that SSO offers.

Single sign-on lets you authenticate once to a central identity provider and then access multiple connected systems without re-entering credentials. After you log in, the identity provider issues a token or assertion that each system trusts, so you can move between applications like email, intranet, or CRM without separate logins. This streamlines workflow and reduces password fatigue, which is why it’s the best fit for logging in once to access many services.

Federated identity is about trust and sharing identity across domains, which enables SSO across organizations, but the mechanism described is the single sign-on capability itself. Two-factor authentication adds an extra verification step, not multi-system access after a single login. Password reuse describes using the same password across services, which does not provide the seamless access across systems that SSO offers.