CCNA AI and Network Operations Practice Question
Exhibit
R1# show ntp status Clock is synchronized, stratum 16, reference is 0.0.0.0 nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**10 ntp uptime is 100 minutes, resolution is 4000 msec reference time is D8C4E1C0.00000000 (12:34:56.000 UTC Mon Mar 15 2021) clock offset is 0.0000 msec, root delay is 0.00 msec root dispersion is 0.00 msec, peer dispersion is 0.00 msec R1# show ntp associations address ref clock st when poll reach delay offset disp *~192.0.2.1 0.0.0.0 16 - 64 0 0.000 0.000 16000. * sys.peer, # selected, + candidate, - outlyer, x falseticker, ~ configured
A network administrator notices that the NTP server on Router R1 is not synchronizing with the upstream NTP server at 192.0.2.1. The router is configured as an NTP client, but show ntp status indicates the clock is unsynchronized and the stratum is 16. There is no firewall between R1 and 192.0.2.1. What is the most likely cause of this issue?
⚠ Common exam trap
Cisco often tests the misconception that NTP configuration alone ensures synchronization, but the trap here is that candidates overlook the prerequisite of IP reachability, assuming the ntp server command handles routing automatically.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Router R1 does not have a route to reach 192.0.2.1.
The most likely cause is that Router R1 lacks a route to the upstream NTP server at 192.0.2.1. Without a valid IP route, NTP packets cannot reach the server, so the client remains unsynchronized with stratum 16. The other options are incorrect: A is not required for client operation, C is irrelevant because NTP version negotiation works across versions, and D is ruled out by the absence of a firewall.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The NTP server at 192.0.2.1 is not configured as a peer on R1.
Why it's wrong here
The output of `show ntp associations` displays a `~` beside 192.0.2.1, which indicates that the peer or server is indeed configured on R1. The fact that it is not reachable is a separate operational issue, not a configuration omission. Re-issuing the `ntp peer` or `ntp server` command would not fix the problem because the configuration already exists; the actual failure is the missing route.
- ✓
Router R1 does not have a route to reach 192.0.2.1.
Why this is correct
For NTP to function, R1 must have a valid IP route to 192.0.2.1 in its routing table. Without that route, outgoing NTP packets are discarded with a 'no route to host' condition, and no replies ever arrive, leaving the server at stratum 16 with a reachability of 0. The `show ntp status` command would report the clock unsynchronized, and `show ntp associations` would show the peer as configured but unreachable.
- ✗
The NTP server at 192.0.2.1 is not using NTP version 4.
Why it's wrong here
NTP version negotiation is inherent in the protocol: NTPv4 clients can communicate with servers running older versions, and a version mismatch would not typically cause the reach register to be zero or the stratum to remain at 16. The output shows the server is reachable (albeit unsynchronized) and there is no indication of a version error in the status flags or association details. Thus, the problem is not the server's NTP version.
- ✗
The NTP server at 192.0.2.1 has a firewall blocking NTP traffic.
Why it's wrong here
A firewall blocking NTP would prevent UDP port 123 traffic, but it would not cause the remote server itself to advertise stratum 16. The reach value of 0 and stratum of 16 indicate that R1 cannot obtain a valid NTP response, which is more consistent with a missing route or an unsynchronized server than a firewall filter. Furthermore, if a firewall were silently dropping packets, R1 would show the server as configured but unreachable, while the server's own stratum would remain independent of the firewall.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Router R1 does not have a route to reach 192.0.2.1.Correct answer▾
Why this is correct
For NTP to function, R1 must have a valid IP route to 192.0.2.1 in its routing table. Without that route, outgoing NTP packets are discarded with a 'no route to host' condition, and no replies ever arrive, leaving the server at stratum 16 with a reachability of 0. The `show ntp status` command would report the clock unsynchronized, and `show ntp associations` would show the peer as configured but unreachable.
✗The NTP server at 192.0.2.1 is not configured as a peer on R1.Wrong answer — click to see why▾
Why this is wrong here
The ntp server command configures the router as a client, not a peer, so peer configuration is not required for synchronization.
Why candidates choose this
Students may confuse the terms 'peer' and 'server' in NTP configuration. They might think that a peer relationship is required for synchronization, but in this scenario, the router is configured as an NTP client, and the server is correctly specified.
✗The NTP server at 192.0.2.1 is not using NTP version 4.Wrong answer — click to see why▾
Why this is wrong here
NTP clients and servers can negotiate versions; using an older version does not prevent synchronization.
Why candidates choose this
Students may recall that NTP version mismatches can cause synchronization failures. However, in this scenario, the reach value of 0 points to a connectivity issue rather than a version mismatch.
✗The NTP server at 192.0.2.1 has a firewall blocking NTP traffic.Wrong answer — click to see why▾
Why this is wrong here
The stem explicitly states there is no firewall, ruling out this cause.
Why candidates choose this
Firewalls are common culprits for blocking NTP traffic in enterprise networks. However, the stratum 16 on the server indicates it is not synchronized to a reliable time source, which is a different issue from firewall blocking.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Agentic AI in Network Operations
Key term
Router
A router is a networking device that connects different networks together and directs data traffic between them by choosing the best path for data to travel.
Key term
Firewall
A firewall is a network security system that monitors and controls incoming and outgoing traffic based on predetermined security rules to protect trusted internal networks from untrusted external networks.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.