Which of the following is the biggest disadvantage of SQL Server…

Concept: SQL Server supports two authentication modes: Windows Authentication and Mixed Mode (which adds SQL Server Authentication). Windows Authentication uses the Windows security architecture and can rely on the Kerberos protocol, via Active Directory Service Principal Names, for mutual authentication and credential delegation. SQL Server Authentication instead validates a username and password stored and managed inside SQL Server itself, and never invokes SSPI (the Windows Security Support Provider Interface).

Application: Because SQL Server Authentication does not use SSPI, it cannot take part in Kerberos-based mutual authentication or ticket delegation across the network -- this is the specific disadvantage being asked about.

• The web-based custom-identity option describes an advantage of SQL Server Authentication (an application manages its own user identities without needing a Windows domain account), not a disadvantage.

• The legacy/third-party compatibility option also describes an advantage (older or third-party software that only understands username-and-password logins can still connect), not a disadvantage.

• "None of the mentioned" is wrong because a genuine disadvantage is present among the options.

Cross-check: Official SQL Server documentation on choosing an authentication mode lists the inability to use Kerberos as a specific limitation of SQL Server Authentication (since it does not use SSPI), while Windows Authentication is documented as supporting Kerberos through Service Principal Names configured in Active Directory -- confirming this asymmetry.

Result: The biggest disadvantage is that SQL Server Authentication cannot use the Kerberos security protocol.