FirstTry
Objective 5.2N10-009

5.2 Given a scenario, troubleshoot common cabling and physical interface issues.

Objective 5.2 sits in Network Troubleshooting, which carries 24% of the Network+ exam. The questions below are original, written from the official objective title above, and each explanation cites the CompTIA page it rests on.

Objective title verbatim from the official objectives. CompTIA exam page ↗

A worked example

Shown solved, with the whole explanation open: this is what every question here carries.

5-2Network TroubleshootingModerate

A technician shuts and reopens this port, and it drops back into the same state within seconds every time. What has to happen first for the port to stay up?

Switch# show interfaces status err-disabled
Port      Name      Status            Reason               Err-disabled Vlans
Gi1/0/9             err-disabled      bpduguard

%PM-4-ERR_DISABLE: bpduguard error detected on Gi1/0/9, putting Gi1/0/9 in err-disable state
Clear the interface counters on the affected portClearing counters resets statistics and leaves port state untouched. It is useful for measuring whether errors are still increasing.
Shorten the errdisable recovery interval to 30 secondsA recovery timer only reenables the port on a schedule, and the same detection fires again while the cause is still present.
Remove the condition that triggered the detectionCorrect · your answerCorrect. The trigger has to go before reenabling will stick.
Move the port into a separate access VLANA different VLAN changes forwarding, not the reason the protection feature acted on that interface.

Correct.

Concept

A port sitting in the error disabled state was shut by the switch itself after a protection feature fired on something it saw. Bringing the interface back is a second step, and it holds only if whatever the feature reacted to has left the link.

Why C

Cycling the interface does nothing about the traffic the feature is set to act on, so the same detection runs again as soon as the link comes up. Dealing with the offending device or cable first is what makes the port stay in service.

Source

#err-disabled#port-status#bpdu-guard#artifact

Now you: objective 5.2 questions

No account needed. The explanation opens when you answer.

Sample question 1 of 3

5-2Network TroubleshootingHard

A wall port has never linked since a refit. A technician runs a cable test from the switch and reads the output below. What should be done next?

[admin@CCR] > interface ethernet cable-test ether2
      name: ether2
    status: no-link
 cable-pairs: open:4,open:4,open:4,open:4

Sample question 2 of 3

5-2Network TroubleshootingModerate

A switch port shows a climbing jabber counter and users on that segment report dropped sessions. What does that counter record?

Sample question 3 of 3

5-2Network TroubleshootingModerate

An uplink shows a rising overflow counter during backup windows, while the checksum and length counters stay flat. Where should the technician look?

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Read the sources

These are the official pages the questions above cite. Reading them is studying the objective from the primary source, which is what the explanations point you toward anyway.

More objectives in Network Troubleshooting