500-445 · Question #42
Which mode must be used for Always On Availability Group clustering?
The correct answer is C. Windows Authentication. Windows Authentication (C) is required because Always On Availability Groups depend on Windows Server Failover Clustering (WSFC), which uses Windows-level security (Kerberos/NTLM) to authenticate communication between cluster nodes - SQL Server logins simply don't exist at the…
Question
Which mode must be used for Always On Availability Group clustering?
Options
- AMixed mode
- BDirectory Connection
- CWindows Authentication
- DSQL Authentication
How the community answered
(21 responses)- A5% (1)
- C95% (20)
Explanation
Windows Authentication (C) is required because Always On Availability Groups depend on Windows Server Failover Clustering (WSFC), which uses Windows-level security (Kerberos/NTLM) to authenticate communication between cluster nodes - SQL Server logins simply don't exist at the OS/cluster layer. SQL Authentication (D) is wrong because SQL logins are instance-local and cannot be recognized by the Windows cluster infrastructure that underpins the AG. Mixed Mode (A) allows both Windows and SQL Authentication, but "allowing" SQL Auth is still incompatible with WSFC's requirement for Windows-level trust - and using Mixed Mode introduces unnecessary risk. Directory Connection (B) is not a real SQL Server authentication mode and serves only as a distractor.
Memory tip: Think "Always On = Always Windows" - the word Always hints at the persistent, domain-level trust that only Windows Authentication can provide across multiple servers.
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