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Err-disabled Recovery Questions

November 25th, 2018 in SWITCH 300-115 Go to comments

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6


In order to turn on errdisable recovery and choose the errdisable conditions, issue this command:
cat6knative#errdisable recovery cause ?

gbic-invalid Enable timer to recover from invalid GBIC error disable state

Reference: https://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/69980-errdisable-recovery.html

Question 7

Question 8


This is the paragraph which describes about the “show errdisable recovery” command on Cisco website:

“If you have enabled errdisable recovery, you can determine the reason for the errdisable status if you issue the “show errdisable recovery” command. An example of the output of this command is shown below:

Switch#show errdisable recovery
ErrDisable Reason    Timer Status
-----------------    --------------
udld                 Enabled
bpduguard            Enabled
security-violatio    Enabled
channel-misconfig    Enabled
pagp-flap            Enabled
dtp-flap             Enabled
link-flap            Enabled
l2ptguard            Enabled
psecure-violation    Enabled
gbic-invalid         Enabled
dhcp-rate-limit      Enabled
mac-limit            Enabled
unicast-flood        Enabled
arp-inspection       Enabled

Timer interval: 300 seconds

Interfaces that will be enabled at the next timeout:

Interface      Errdisable reason      Time left(sec)
---------    ---------------------    --------------
  Fa2/4                bpduguard          273

Reference: https://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/69980-errdisable-recovery.html

So answer A seems to be correct but the above quote is very misleading. In fact, this command is used to verify which services/features were enabled for err-disable recovery (notice that the err-disable recovery feature is disabled by default for all services and features and we have to manually turn them on if we want to use via the command “errdisable recovery cause …”). If we allows all above services/features to automatically recover then we will not know the reason a port was error-disabled.

In fact, the best way to determine why a port is in the err-disabled state is to view the Syslog messages. For example:

%PM-4-ERR_DISABLE: psecure-violation error detected on Fa0/1, putting Fa0/1 in err-disable state

This means Fa0/1 is put in err-disabled state because of a port security violation.

Note: The command “show errdisable detect” is used to identify which services are enabled for Errdisable only (for example, services like “arp-inspection”, bpduguard, UDLD,…)

Question 9


When a port is error-disabled, the LED associated with the port on the front panel is solid orange.

Reference: https://www.cisco.com/c/en/us/support/docs/lan-switching/ethernet/12017-20.html

Error-disabled is same as shut down state so all traffic on this port are stopped.

Question 10


When a port security is violated, that port can be put into errdisable state -> B is correct.

When a maximum number of hosts per port was reached, learning a new MAC address can put that port into errdisable state -> D is correct.

  1. tcp22
    December 4th, 2018

    A question about a fiber connected EtherChannel after the switches were powered on the ports went errdisable.
    A. Due to UDLD errdisable it.
    B. Due to EtherChannel misconfig.

    why B is not correct?

  2. driguilim
    December 5th, 2018

    Where can I see thi question about “Err-disabled Recovery Questions”? I’ve got the lastest download from the PDF questions (SWITCH_Nov_2019), but I didn’t found any topic about it.

  3. ccnp engineer
    December 10th, 2018

    Which errdisable recovery command option enables a device to recover from an incorrect SFT state?

    A. link-monitor-failure
    B. sfp-config-mismatch
    C. gbic-invalid
    D. port-mode-failure

    I think the answer should be C ( gbic-invalid) not A.

    Please verify and confirm..

    Reference link below…

  4. Anonymous
    December 12th, 2018

    @CCNP Engineer

    I thought the same thing when I read. Can someone confirm?

  5. patan
    December 15th, 2018

    i also think gbic-invalid is the correct answer. I donĀ“t see “link-monitor-failure” is a valid errdisable recovery command.
    Someone else could please confirm?

  6. Anonymous
    December 19th, 2018

    Which errdisable recovery command option enables a device to recover from an incorrect SFT state?
    A. link-monitor-failure
    B. sfp-config-mismatch
    C. gbic-invalid
    D. port-mode-failure

    Hi May i know the true answer to this one?
    says that the right answer is C.GBIC-INVALID however here in certprepare the answer is ‘A’


  7. Choochin
    December 22nd, 2018

    For question 8:

    You can issue a show log
    Check the Syslog server
    You can issue show errdisable recovery.

    show errdisable recovery is the preferred method because it’s the most straight forward when you are on the switch and the disablement may have cut access to a syslog server. It will show you all recovery options that are enabled and all current disabled ports.

  8. Anonymous
    January 10th, 2019

    Is Answers to Question 8 correct? I think it should be B & C?

  9. RS
    January 13th, 2019

    I am not able to understand where are the questions ?
    Where to find the questions ?

  10. RS
    January 13th, 2019

    Is it required to get registered to view the questions ?

  11. Nick
    January 16th, 2019

    Where can we find the questions ?

  12. Anonymous
    January 17th, 2019

    About the question 6, nobody knows if the correct answer is c?

    I really think that the option “c” is more suitable.

  13. Wastel
    January 21st, 2019

    Which errdisable recovery command option enables a device to recover from an incorrect SFT state?

    A. link-monitor-failure (abnormal SPAN Port usage )
    B. sfp-config-mismatch (might result from non-cisco compatible SFP)
    C. gbic-invalid
    D. port-mode-failure

    2960G# show errdisable detect

    ErrDisable Reason Detection Mode
    —————– ——— —-
    bpduguard Enabled port
    channel-misconfig Enabled port
    community-limit Enabled port
    dhcp-rate-limit Enabled port
    dtp-flap Enabled port
    gbic-invalid Enabled port
    inline-power Enabled port
    invalid-policy Enabled port
    link-flap Enabled port
    loopback Enabled port
    lsgroup Enabled port
    mac-limit Enabled port
    pagp-flap Enabled port
    port-mode-failure Enabled port
    secure-violation Enabled port/vlan
    security-violation Enabled port
    sfp-config-mismatch Enabled port
    small-frame Enabled port
    storm-control Enabled port
    udld Enabled port
    vmps Enabled port

    Which one is related to “SFT state” ??? is it a typo??? SFP=SmallFormfactorTranceiver

    A. Solution: check if you have a monitor port configuration on the switch (SPAN Port)
    #sh monitor detail (can’t see any relation to SFT)
    B. Solution: configuration to allow SFPs that do not pass IOS’s check for Cisco SFPs.

    Router(config)# service unsupported-transceiver
    Router(config)# no errdisable detect cause gbic-invalid
    Router(config)# errdisable recovery cause gbic-invalid
    Router(config)# no errdisable detect cause sfp-config-mismatch
    Router(config)# errdisable recovery cause sfp-config-mismatch

    C. GBICs -see B.
    D. might be related toTrunk configuration (can’t see any relation to SFT)
    At least not matching native vlan trunk configurations of two connected switches will cause security issues. Trunkports might be disabled if detected and err-disabled is enabled (Haven’t testet it on two real switches yet)

    My tip for this Question: its a typo – read it:

    Which errdisable recovery command option enables a device to recover from an incorrect SFP state? – B

  14. Anonymous
    January 29th, 2019

    I just take the exam today and I fail, just to let you know thaht the IPHelper guide and the Pass Leader document that has 5 PDF are not enough. There are a lot of question that are not in these guides, Just study more and looking for new questions guides :( :(

  15. ugurdy
    February 2nd, 2019

    I agree with Wastel. It is probably a typo and should be “SFP State” and since it can be either GBIC or SFP, then the answer should be “B”.

  16. junborg
    February 25th, 2019

    In Question 10: learned a new MAC address is the same and part of a port security violation!!!! sticky-mac-address

    A. It is connected to a host with an NIC that is unable to recognize
    B. The switch incurred a port security violation
    C. It detected a collision
    D. It learned a new MAC address
    E. It detected a peer with a matching duplex

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    March 15th, 2019

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    March 24th, 2019

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    April 9th, 2019

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    April 9th, 2019

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    April 30th, 2019

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  22. Anonymous
    July 21st, 2019


    There are various reasons for the interface to go into errdisable. The reason can be:
    Duplex mismatch <<<>> Answer B

    I think B and E are better choices.

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    August 1st, 2019

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    September 6th, 2019

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  25. Stranger_83
    September 8th, 2019

    Question 10
    Looks like correct answer are B and C.

    Learning new MAC (answer C) itself without port security violation doesn`t trigger err-disabled status while detected collision does.

    So correct variants are:

    B. The switch incurred a port security violation
    C. It detected a collision

  26. CJ
    September 13th, 2019

    @Stranger_83: Collisions will not put port into err-disabled state.
    You can check this by issuing command: show errdisable detect. [it will show you possible reasons for err-disable state]

    For Q10, you should combine option B and D.
    – Port has Port-Security enabled
    – AND it’s learned new MAC address [above the allowed limit, which is 1 by default, when Port Security is enabled]

  27. deuteros
    September 18th, 2019

    witch two statements about recovering error-disabled interfaces are true?
    a) the show errdisable recovery command displays the conditios for which autorecovery is enabled
    b) reloading the switch it from the error

  28. Efiko
    September 20th, 2019

    Extract from: https://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/69980-errdisable-recovery.html

    Causes of Errdisable
    This feature was first implemented in order to handle special collision situations in which the switch detected excessive or late collisions on a port. Excessive collisions occur when a frame is dropped because the switch encounters 16 collisions in a row. Late collisions occur after every device on the wire should have recognized that the wire was in use. Possible causes of these types of errors include:

    A cable that is out of specification (either too long, the wrong type, or defective)
    A bad network interface card (NIC) card (with physical problems or driver problems)
    A port duplex misconfiguration
    A port duplex misconfiguration is a common cause of the errors because of failures to negotiate the speed and duplex properly between two directly connected devices (for example, a NIC that connects to a switch). Only half-duplex connections should ever have collisions in a LAN. Because of the carrier sense multiple access (CSMA) nature of Ethernet, collisions are normal for half duplex, as long as the collisions do not exceed a small percentage of traffic.
    There are various reasons for the interface to go into errdisable. The reason can be:
    Duplex mismatch
    Port channel misconfiguration
    BPDU guard violation
    UniDirectional Link Detection (UDLD) condition
    Late-collision detection
    Link-flap detection
    Security violation
    Port Aggregation Protocol (PAgP) flap
    Layer 2 Tunneling Protocol (L2TP) guard
    DHCP snooping rate-limit
    Incorrect GBIC / Small Form-Factor Pluggable (SFP) module or cable
    Address Resolution Protocol (ARP) inspection
    Inline power

    So “C. gbic-invalid” seems correct for question 6.

    As for question 10, a single collision won’t cause for port to errdisable, rather Excessive collision will and by excessive collision, it has to be like 16 collisions in a row. So I will be tempted to pick options B and D, which both seem to suggest that port security have been configured on the switch.

  29. Dmytro
    September 23rd, 2019

    Q8 and Q5 are the similar, why we have a different answers?
    I think Q8 right answers are A and C.

  30. Dmytro
    October 22nd, 2019

    Q4 both variants are correct answers.

  31. Omar
    October 30th, 2019

    A. You can use the show errdisable recovery command to view the reason a port was error-disabled.
    B. Errdisable detection is enabled by default on ports with port security enabled
    C. You can use the show errdisable detect command to view the reason a port was error-disabled.
    D. Errdisabled autorecovery is enabled by default.
    E. Errdisabled detection is disabled by default on ports with port security enabled

    The solution says that A & B are correct but I think that B & C. What do you think?

  32. Nick
    November 10th, 2019

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    aparna @ germanyxon . com

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  33. Mimitsous
    November 12th, 2019

    Hello everyone,

    Does premium membership include all questions? old + new ?
    And do we get to practice the labs here, or we need to simulate them on packet tracer or GNS3 ?

    Thank you

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