Home > Troubleshooting Questions

Troubleshooting Questions

February 6th, 2017 Go to comments

Question 1

Explanation

At the end of each frame there is a Frame Check Sequence (FCS) field. FCS can be analyzed to determine if errors have occurred. FCS uses cyclic redundancy check (CRC) algorithm to detect errors in the transmitted frames. Before sending data, the sending host generates a CRC based on the header and data of that frame. When this frame arrives, the receiving host uses the same algorithm to generate its own CRC and compare them. If they do not match then a CRC error will occur. CRC errors (and input errors in general) are often caused by duplex mismatch or Physical layer issues (like faulty cable, faulty network interface card or excessive interference during the transmission,…).

On an Ethernet connection, a duplex mismatch is a condition where two connected devices operate in different duplex modes, that is, one operates in half duplex while the other one operates in full duplex.

Note:
+ Runts are frames which do not meet the minimum frame size of 64 bytes. Runts are usually created by collisions.
+ Giants: frames that are larger than 1,518 bytes

Question 2

Explanation

The ports on the switch are not up indicating it is a layer 1 (physical) problem so we should check cable type, power and how they are plugged in.

Question 3

Question 4

Question 5

Question 6

Explanation

The “show ip nat statistics” only gives us information about NAT translation. We cannot know if IP routing is enabled or the VLANs are up not not.

The “show ip statistics” command does not exist.

In the Troubleshoot part of “How to configure InterVLAN Routing on Layer 3 switches” (http://www.cisco.com/c/en/us/support/docs/lan-switching/inter-vlan-routing/41860-howto-L3-intervlanrouting.html) Cisco recommends to use the “show ip interface brief” command as follows:
Also verify the interface VLAN status by issuing the show ip interface brief command.
+ If the interface status is administratively down, enter the no shutdown command in the VLAN interface configuration mode.
+ If the interface status is down/down, verify the VTP configuration and that the VLANs have been added to the VLAN database. Check to see if a port is assigned to the VLAN and whether it is in the Spanning Tree forwarding state.

Initiate a ping from an end device in one VLAN to the interface VLAN on another VLAN in order to verify that the switch routes between VLANs. In this example, ping from VLAN 2 (10.1.2.1) to Interface VLAN 3 (10.1.3.1) or Interface VLAN 10 (10.1.10.1). If the ping fails, verify that IP routing is enabled and that the VLAN interfaces status is up with the show ip interface brief command.

Also in the above link Cisco only mentions about the “show ip route” in the “Verify” part, not “Troubleshooting” part so “show ip interface brief” is a better answer.

Question 7

Explanation

In fact all three of the above answers are in the problem-solving process but “gather facts” is at Step 2 while “Create an action plan” and “Implement an action plan” is at step 4 & 5 of this link http://www.cisco.com/en/US/docs/internetworking/troubleshooting/guide/tr1901.html

Step 2 Gather the facts that you need to help isolate possible causes.
Ask questions of affected users, network administrators, managers, and other key people. Collect information from sources such as network management systems, protocol analyzer traces, output from router diagnostic commands, or software release notes.

Comments (7) Comments
  1. anonymous
    February 19th, 2017

    for Question 1 I’ve seen many other places give the answer of “late collisions”, such as here http://vceguide.com/which-interface-counter-can-you-use-to-diagnose-a-duplex-mismatch-problem/

    Can you confirm the right answer?

  2. Sisi
    February 23rd, 2017

    For Question 6:

    “Initiate a ping from an end device in one VLAN to the interface VLAN on another VLAN in order to verify that the switch routes between VLANs. In this example, ping from VLAN 2 (10.1.2.1) to Interface VLAN 3 (10.1.3.1) or Interface VLAN 10 (10.1.10.1). If the ping fails, verify that IP routing is enabled and that the VLAN interfaces status is up with the show ip interface brief command.”

    http://www.cisco.com/c/en/us/support/docs/lan-switching/inter-vlan-routing/41860-howto-L3-intervlanrouting.html

    So the correct answer would be A

  3. @theunreal
    March 4th, 2017

    @anonymous: I wa thinkin the same, but checking directly from Cisco ICDN2 material they gave me during the class: I can read that both input errors (CRC errors) and output errors (late collision) usually indicate a duplex mismatch issue, so I think that both arecorrect. But I don’t know if at the exam can exist a single-answer question with more that one correct option.

  4. real name
    March 13th, 2017

    i see no questions… only explanations

  5. New*Dumps
    April 4th, 2017

    DOWNLOAD Files at below link
    100%, guaranteed passing material get Download package, (AllinONE) that you need to clear exam.
    All LABS in Packet Tracer
    VCE + PDF

    http://bridgeurl.com/ccna

  6. Acrina
    May 3rd, 2017

    Watched the complete Cisco CCNA 200-125 exam online classes with each and every detail about 200-125 CCNA exam only on: https://www.youtube.com/watch?v=fg2uoWDHFeU

    Video Credit: Testmayor.com

  7. LKB
    May 25th, 2017

    I don’t see any questions. Please help?