Which Two Actions Guarantee Cluster Time Synchronization in Grid Infrastructure 19c?
Which two actions guarantee that time is synchronized properly on all nodes in a cluster after installing Oracle Grid Infrastructure 19c? (Choose two.)
Community Votes
83% of anonymous learners picked answer DE. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
Tests CTSSD's automatic mode selection — NTP active means observer mode, NTP absent means active mode — and the trap is assuming CTSSD falls back to active mode when configured NTP time servers merely become unreachable.
In Oracle Grid Infrastructure 19c, Cluster Time Synchronization Service Daemon (CTSSD) runs in observer mode when NTP is configured on all cluster nodes and in active mode when NTP is deactivated. This page establishes that configuring NTP or deactivating NTP are the two actions that guarantee cluster-wide time synchronization.
Learners often choose A or C, believing any NTP misconfiguration or unreachable time server makes CTSSD start in active mode; in fact CTSSD only runs active when the NTP daemon itself is not active, so NTP must be deactivated or deinstalled.
Community Discussion (4 comments)
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Expert Analysis
Why the Answer Is Correct
Options D and E match the documented CTSSD behavior in Oracle Grid Infrastructure 19c. When NTP is configured and running on every cluster node, the installer starts CTSSD in observer mode, where it monitors NTP but does not discipline the clock itself, so synchronized NTP guarantees cluster time sync. When NTP is deactivated or deinstalled on all nodes, CTSSD automatically starts in active mode and synchronizes time across the cluster without NTP. Those two mutually exclusive configurations are exactly what the question asks for, which is why the correct pair is D and E.Why the Other Options Are Wrong
Option A is a classic distractor: CTSSD chooses its mode based on whether the NTP daemon is active, not on whether configured time servers answer queries, so unreachable NTP servers leave NTP active and CTSSD remains in observer mode. Option C says NTP is "not configured properly," which is too vague; Oracle's rule is that NTP must be inactive — deactivated and deinstalled — for CTSSD to take over in active mode, and a running-but-misconfigured NTP daemon still forces observer mode. Option B is impossible because the DBA cannot manually start CTSSD in active mode while NTP is running; CTSSD starts automatically at clusterware startup and would select observer mode in that scenario.Community Comment Notes
As krwi1 noted, the Oracle documentation states that if you have NTP daemons but cannot configure them to synchronize with a time server, you should "deactivate and deinstall the NTP" so CTSSD takes over. jackhsu0704 summarized the binary mapping directly: "D: if NTP==> CTSSD is observer E: If no NTP: CTSSD is active." Test_1 also confirmed the DE consensus, while Tunglinfo9 selected CD and quoted the same deinstall-NTP passage, inadvertently showing why E is stronger than C because the documented action requires NTP to be inactive, not merely misconfigured.Official Reference
Exam Strategy
Memorize the binary rule: NTP active equals CTSSD observer mode, NTP inactive equals CTSSD active mode. On multi-select questions, eliminate any choice where a DBA manually starts or stops CTSSD, because its mode is selected automatically when clusterware starts.
Frequently Asked Questions
Why doesn't CTSSD switch to active mode when NTP servers are unreachable?
CTSSD decides its mode by checking whether the NTP daemon is active, not whether configured time servers respond, so unreachable servers leave CTSSD in observer mode.
Can I manually start CTSSD in active mode while NTP is still running?
No. CTSSD starts automatically at clusterware startup and selects observer mode when NTP is active; you must deactivate NTP on all nodes for active mode.