Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
Exhibit
show ntp associations address ref clock st when poll reach delay offset disp *~10.10.50.5 .INIT. 16 - 64 0 0.000 0.000 16000 Configured server: 10.10.50.5
Exhibit: A switch shows a clock that is several minutes off from other devices even though an NTP server has been configured. Which issue is the most likely cause?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
The NTP server is unsynchronized or unreachable
Reach 0 and stratum 16 indicate no useful time source is being reached.
B
Distractor review
The device must run Syslog before NTP can sync
Syslog is unrelated.
C
Distractor review
NTP requires a trunk port on the management VLAN
NTP needs IP reachability, not a trunk specifically.
D
Distractor review
The clock can sync only if DNS is configured
NTP uses IP connectivity; DNS is optional if using addresses.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting options that mention unrelated features such as Syslog, VLAN trunking, or DNS as prerequisites for NTP synchronization. Candidates might incorrectly believe that Syslog must run before NTP or that VLAN trunk ports are required for management VLAN NTP traffic. Another tempting mistake is assuming DNS must be configured for NTP to resolve server names. In reality, NTP depends solely on IP connectivity to a synchronized server. Misunderstanding the significance of NTP stratum levels and ignoring ACL or routing issues leads to incorrect conclusions about why the clock is off.
Technical deep dive
How to think about this question
Network Time Protocol (NTP) is a critical IP service used to synchronize the clocks of network devices to a reliable time source. Accurate timekeeping is essential for logging, security protocols, and time-sensitive applications. NTP operates by exchanging timestamped packets between clients and servers, adjusting the local clock to match the server’s time. Cisco devices use NTP to maintain consistent time across the network, which is vital for troubleshooting and event correlation. For NTP to function correctly, the client device must have IP reachability to a synchronized NTP server. This means the server must be reachable via routing and not blocked by access control lists (ACLs). The NTP server must itself be synchronized to a valid time source, indicated by a stratum level less than 16. If the server is unreachable or unsynchronized (stratum 16), the client device cannot update its clock and will continue to drift, showing incorrect time. A common exam trap is assuming that enabling NTP configuration alone guarantees synchronization. In reality, network connectivity issues, ACLs blocking UDP port 123, or an unsynchronized NTP server cause the device to keep its local clock, which can be minutes off. Practical troubleshooting involves verifying NTP status, checking stratum levels, and ensuring IP connectivity to the NTP server. Understanding these behaviors helps avoid misdiagnosing unrelated features like Syslog, VLAN trunks, or DNS as causes of NTP sync failure.
KKey Concepts to Remember
- NTP requires IP reachability to a synchronized time source to update the local device clock accurately.
- A device configured with an unreachable or unsynchronized NTP server will retain its local clock, causing time drift.
- NTP stratum levels indicate the distance from the authoritative time source; stratum 16 means no valid time source is reachable.
- ACLs or routing issues can block NTP packets, preventing synchronization even if the server is configured.
- Syslog is unrelated to NTP synchronization and does not affect the device’s ability to sync time.
- NTP synchronization depends on IP connectivity, not on VLAN trunking or specific VLAN configurations.
- DNS is optional for NTP if IP addresses are used directly; lack of DNS does not prevent NTP sync.
- Monitoring NTP status commands helps verify synchronization state and troubleshoot connectivity or configuration issues.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
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FAQ
Questions learners often ask
What does this 200-301 question test?
NTP requires IP reachability to a synchronized time source to update the local device clock accurately.
What is the correct answer to this question?
The correct answer is: The NTP server is unsynchronized or unreachable — NTP requires IP reachability to the time source. If the NTP server is configured but unreachable because of routing or ACL issues, the device keeps its local clock and drifts away from the rest of the network.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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