Troubleshooting NTP Time Updates After New Configuration
Short answer
C Configuring NTP authentication on the network device causes the loss of time updates due to unconfigured or mismatched authentication keys.
Question
longer processing time updates. What is the cause of this issue?
Key Takeaways
The key trap is distinguishing between 'new configuration' applied to the client versus the server; enabling auth on the client (C) immediately stops updates if the server isn't configured to accept it or if keys don't match.
This question tests the impact of enabling NTP authentication on a network device that previously synchronized without it. The correct answer is C because configuring authentication requires matching keys, which breaks association if not properly set up.
Common mistake: Many learners choose D, assuming the server changed settings, but the prompt explicitly states the administrator was testing new configuration on the network device.
Expert Analysis
Why the Answer Is Correct
Correct answer: C — Configuring NTP authentication on the network device causes the issue because the device now expects authenticated time sources. If the NTP server is not configured with matching keys or if the device's new configuration does not include valid key IDs, the association fails and time updates are no longer processed.
Why the Other Options Are Wrong
Option A is incorrect because changing stratum levels does not break an existing association unless specific filtering policies are in place. Option B is unlikely because 'new configuration' implies adding features like authentication rather than modifying an existing password, which would be described as a change to existing settings. Option D contradicts the scenario premise that the administrator was testing changes on the network device, not the server.
Community Comment Notes
Several users like cyberwhizzy0 and ffaiz correctly identified C by focusing on the phrase 'new configuration' being performed on the device, noting that this implies adding authentication for the first time. Others like Badrach argued for B, suggesting a password change, but this is less consistent with standard exam phrasing where 'new configuration' typically refers to enabling security features. Users like ITPro21 chose D, mistakenly assuming the server side was modified despite the clear focus on the device.
Exam Strategy
Always identify WHERE the configuration change occurred. If the prompt says 'admin tested new config on device,' look for options that involve enabling new features on that device, such as authentication or ACLs.
Frequently Asked Questions
Why doesn't changing NTP stratum break the association?
What if the admin changed the password instead?
Discussion 10 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 10
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cyberwhizzy0 👍 3 Answered CThe new configuration was done on the network device, so whatever caused the loss of communication happened on the client, that left us with B and C. What was done on the network device was a new configuration not modification of existing configuration. B means the server and network device would have had a password configured and it was modified on the device but since it is a new setting, that leaves us with option C. This means NTP authentication was configured on the device but yet to be implemented on the server
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ffaiz 👍 3 Answered CIn my opinion, new configuration means, some new feature has been configured, which in this case is authentication. That's why NTP ain't working. If "auth" was already configured then - we can't say "entering the wrong password" would qualify as a new configuration. It is a very tricky question, with not a lot of details.
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Hereim 👍 3I think it should be D. NTP authentication added on the server must be the cause for the update no longer happening on the given network device, assuming there was no change on the network device (that's how the question seems to be framed).
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Hereim 👍 3Sorry missed out reading "new configuration" being tested on the network device....Ans should be C in that case...
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Badrach 👍 2 Answered BCorrect answer should be B, not D because the configuration was not done in the NTP server and not C because the network device had a previously established association with the NTP server before testing the new configuration which means NTP authentication was already configured before so the only thing that could have cause this is if he changed the password on the network device
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F0rtyx40 👍 1 Answered CThis is interesting, we have no clue if authentication is/was used previously on the "network device" and we cant see any configurations. This is literally a shot in the dark question but i believe they think the more likely situation to be C, why someone would configure NTP auth when they don't need it is beyond me.
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XBfoundX 👍 1 Answered CThe answer is C, this new config added for sure the NTP authentication to the switch or the router and now, is not able to sync with the NTP server due to the fact that the router or the switch is using NTP auth.
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Nian 👍 1Makes sense.. The situation must be that there were no authentication required previously (hence it worked)- but now it is required due to change on the NTP server side
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044f2fc 👍 1Configuration change not password change and it is happening in network device and no where it mentioned that authentication was configured earlier..
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ITPro21 👍 1 Answered DOpinion - The network device had a previously established association with the NTP server, therefore it has to be a change on the server side.
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