| Date of Issue: 03-01-2023 | Rate this Study Guide |
Question 1.
The output below shows which of the following about NTP on this router?
router#show ntp stat Clock is unsynchronized, stratum 16, no reference clock nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**16 reference time is 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900) clock offset is 0.0000 msec, root delay is 0.00 msec root dispersion is 0.00 msec, peer dispersion is 0.00 msec
| a) | This router is not configured for NTP. |
| b) | This router is configured for NTP, but the source NTP server is only stratum 16. |
| c) | This router has an NTP server or peer configured, but either is not yet synchronized with the server or peer, or the router can't reach the server or peer. |
| d) | This router is configured as an NTP master as indicated by the "no reference clock" portion of the display. |
Question 2.
When a router crashes, IOS has a feature known as a "core dump" which lets us save a copy of the memory by sending it to an external server. The IOS core dump feature works much like the UNIX core dump feature. Which of the following are true regarding the use of core dumps?
| a) | The router must have an account on an external server that permits FTP, TFTP, or RCP. |
| b) | The external server must have disk space available at least equal to the router's memory. |
| c) | A router configured for core dump must be redundant because a core dump can take a long time e.g. 30 minutes. |
| d) | A and B |
| e) | All the above |
Question 3.
The following command output indicates that this network is which of the following?
Router# show access-list 2010
permit icmp any any echo (21445 matches)
permit icmp any any echo-reply (12 matches)
permit ip any any (4312 matches)
| a) | The end target of a Smurf Attack |
| b) | The reflector for a Smurf Attack |
| c) | The end target of a Fraggle Attack |
| d) | The reflector for a Fraggle Attack |
Answers
Question 1.
The output below shows which of the following about NTP on this router?
router#show ntp stat Clock is unsynchronized, stratum 16, no reference clock nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**16 reference time is 00000000.00000000 (00:00:00.000 UTC Mon Jan 1 1900) clock offset is 0.0000 msec, root delay is 0.00 msec root dispersion is 0.00 msec, peer dispersion is 0.00 msec
| a) | This router is not configured for NTP. |
| b) | This router is configured for NTP, but the source NTP server is only stratum 16. |
| c) | This router has an NTP server or peer configured, but either is not yet synchronized with the server or peer, or the router can't reach the server or peer. |
| d) | This router is configured as an NTP master as indicated by the "no reference clock" portion of the display. |
| c) | This router has an NTP server or peer configured, but either is not yet synchronized with the server or peer, or the router can't reach the server or peer. |
Explanation
Choice C is the only correct answer. We cannot tell from the output of this command alone whether the router is configured as an NTP peer or server. But, we can tell that at least one of the two is configured as seen by the fact that NTP is unsynchronized, the router is using stratum 16, and no reference clock is listed. The router either may not have synchronized with the NTP server or peer, or the NTP server or peer may be unreachable.
Choice A is tempting, but incorrect because if no NTP server or peer were configured, then when we issue this command, we would get nothing back as a response.
Choice B is wrong because we only see stratum 16 when either the NTP server or peer is unsynchronized or unreachable. You will rarely see a stratum lower than 4 for a functioning NTP server or peer.
Choice D is wrong because, if the router were configured as an NTP master, the stratum would be 1.
[4526]
Question 2.
When a router crashes, IOS has a feature known as a "core dump" which lets us save a copy of the memory by sending it to an external server. The IOS core dump feature works much like the UNIX core dump feature. Which of the following are true regarding the use of core dumps?
| a) | The router must have an account on an external server that permits FTP, TFTP, or RCP. |
| b) | The external server must have disk space available at least equal to the router's memory. |
| c) | A router configured for core dump must be redundant because a core dump can take a long time e.g. 30 minutes. |
| d) | A and B |
| e) | All the above |
| d) | A and B |
Explanation
This is an intentionally vague question. The Cisco exams do not test you on what is possible or even preferable. They test you on what is "correct". Certainly choices A and B are correct. Choice C is the difficult choice. Yes, a core dump can take a long time, during which the router will be down. A good design should have redundant routers to allow for the possibility of a core dump without impacting the network, but it is not a necessity. The key word must in choice C should tell you that this choice is wrong and that choice D is the best answer for this question.
[4536]
Question 3.
The following command output indicates that this network is which of the following?
Router# show access-list 2010
permit icmp any any echo (21445 matches)
permit icmp any any echo-reply (12 matches)
permit ip any any (4312 matches)
| a) | The end target of a Smurf Attack |
| b) | The reflector for a Smurf Attack |
| c) | The end target of a Fraggle Attack |
| d) | The reflector for a Fraggle Attack |
| b) | The reflector for a Smurf Attack |
Explanation
Only a Smurf attack uses ICMP packets. A Fraggle attack uses UDP packets. We can tell that we are the reflector for the Smurf attack because there is a much higher ratio of ICMP echo packets to ICMP echo reply packets. If this were reversed, then we would be the end target of the Smurf attack.
[4540]
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