Free Troubleshooting Cisco Data Center Infrastructure Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Troubleshooting Cisco Data Center Infrastructure practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1Two Nexus 7000 OSPF neighbors remain in Exstart/Exchange after an interface MTU change. Small pings succeed, but packets matching the intended link MTU fail. Which issue should be corrected?

   1. A. An inconsistent OSPF hello interval
   2. B. An MTU mismatch along the adjacency path
   3. C. An inconsistent OSPF area identifier
   4. D. An authentication key mismatch on the link

   Answer: B

   Explanation: Cisco lists "MTU mismatch - EXCHANGE" under Exstart/Exchange problems. The MTU change and size-dependent failure point to MTU compatibility, rather than initial hello, area, or authentication checks.

   Reference: Nexus 7000 OSPF Adjacency Issues Troubleshoot — OSPF Neighbor Stuck in Exstart/Exchange

2. 2Cisco IMC reports a C-Series DIMM as degraded because of correctable errors. How does this differ from an inoperable DIMM with uncorrectable errors in the documented behavior?

   1. A. The DIMM is removed from OS use despite its correctable errors
   2. B. The DIMM stays available to the OS despite its degraded status
   3. C. The DIMM is available only after the correctable-error flag is cleared
   4. D. The DIMM stays installed but contributes no effective OS memory

   Answer: B

   Explanation: Correctable-error DIMMs are "not disabled" in this documented behavior and remain usable by the OS. Degraded status does not mean disabled capacity, nor does it require clearing the flag before the OS can use the DIMM.

   Reference: Cisco UCS C-Series Servers Troubleshooting Guide — Troubleshooting Server Hardware or Software Issues — Troubleshooting Degraded DIMM Errors; Troubleshooting Inoperable DIMMs Errors

3. 3A Fibre Channel port has frames queued but its remaining transmit BB_credit count is zero. What must occur before it can transmit another frame under normal credit-based flow control?

   1. A. Reception of an R_RDY primitive returning a buffer credit
   2. B. Reception of a FLOGI acceptance assigning a fabric address
   3. C. Reception of a FDISC acceptance assigning another virtual N_Port address
   4. D. Completion of an ELP exchange negotiating inter-switch link parameters

   Answer: A

   Explanation: Cisco identifies "R_RDY" as the buffer-credit return. Under normal established-link flow control, zero transmit credits require a returned credit. Fabric login, virtual-port login, and link-parameter exchange do not serve as that per-buffer credit return.

   Reference: Cisco MDS 9000 Series Interfaces Configuration Guide, Release 9.x — Congestion Management — Congestion Overview — Buffer-to-Buffer (BB) credits

4. 4An NX-OS EEM policy matches the intended event but contains no action statements. Why does it observe the event without performing a recovery operation?

   1. A. An event match itself confirms that the policy’s recovery operation completed
   2. B. An event statement defines the recovery command as well as its trigger
   3. C. An event statement selects a trigger; action statements define the response
   4. D. An action statement changes event matching rather than executing a response

   Answer: C

   Explanation: A policy without action statements "takes no actions". Event matching selects when a policy triggers; it does not define or prove execution of a repair. Action statements provide the responses.

   Reference: Cisco Nexus 9000 Series NX-OS System Management Configuration Guide, Release 10.3(x) — Configuring the Embedded Event Manager — Embedded Event Manager — Action statements

5. 5Before installing a candidate NX-OS image on a Nexus 9000, an engineer must check the upgrade's compatibility and impact without performing the installation. Which command serves this purpose?

   1. A. show version
   2. B. show install all impact nxos bootflash:image.bin
   3. C. install all nxos bootflash:image.bin
   4. D. copy running-config startup-config

   Answer: B

   Explanation: The guide uses "show install all impact" before the actual upgrade. Show version reports current software; install all initiates installation, and saving configuration does not evaluate the candidate image.

   Reference: Cisco Nexus 9000 Series NX-OS Software Upgrade and Downgrade Guide, Release 10.3(x) — Upgrade NX-OS software — Step 5

6. 6An OSPF neighbor does not appear on a Nexus 7000. Both ends use the same subnet, area, area type, and authentication. One interface uses hello/dead intervals of 10/40 seconds; the other uses 5/20 seconds. Which change addresses the mismatch?

   1. A. Assign the same router ID to both switches
   2. B. Increase the reference bandwidth on both switches
   3. C. Configure matching hello and dead intervals
   4. D. Assign a higher DR priority to one switch

   Answer: C

   Explanation: Cisco identifies "Mismatched hello/dead interval" as an adjacency problem. Matching these intervals addresses the observed discrepancy. Router IDs should remain distinct; reference bandwidth and DR priority do not reconcile hello/dead timers.

   Reference: Nexus 7000 OSPF Adjacency Issues Troubleshoot — OSPF Adjacency Does Not Come Online; Check the OSPF Configuration

7. 7A newly installed DIMM is not recognized in a UCS C-Series server. Its model and orientation are correct, but it was placed in a slot belonging to an uninstalled processor. What should be corrected?

   1. A. Move the DIMM to a supported slot belonging to an installed CPU
   2. B. Keep the DIMM in that slot and clear its correctable-error flag
   3. C. Keep the slot assignment and reseat a higher-capacity supported DIMM
   4. D. Keep the slot assignment and populate its paired channel slots

   Answer: A

   Explanation: Cisco requires an "active CPU" for the DIMM slot. Clearing an error flag, changing capacity, or adding paired DIMMs does not connect a slot belonging to an absent CPU. Use a supported population arrangement for an installed CPU.

   Reference: Cisco UCS C-Series Servers Troubleshooting Guide — Troubleshooting Server Hardware or Software Issues — Recommended Solutions for DIMM Issues — DIMM is not recognized

8. 8Two FC ports have the same number of transmit-credit transitions to zero. An engineer needs to compare how long each port was unable to transmit queued frames. Which measurement best supplies that missing duration?

   1. A. The Tx transitions-to-zero event count
   2. B. The timeout-drop frame count
   3. C. The TxWait time counter
   4. D. The credit-loss-recovery event count

   Answer: C

   Explanation: Cisco defines "TxWait" as time with queued frames that cannot be transmitted. Transitions-to-zero, recovery events, and timeout drops count occurrences or discarded frames rather than this accumulated waiting duration.

   Reference: Cisco MDS 9000 Series Interfaces Configuration Guide, Release 9.x — Congestion Management — Congestion Overview — TxWait; Congestion Detection — transitions to zero

9. 9An NX-OS EEM policy with a single untagged CLI-match event logs a matched command, but the original command does not execute. The policy should observe the command and still allow its default behavior. Which action is missing?

   1. A. event-default
   2. B. counter
   3. C. policy-default disable
   4. D. forceshut

   Answer: A

   Explanation: Cisco requires "event-default" to permit the default behavior of a matched CLI command. Counter operations and shutdown actions do not allow the original command; disabling default policy handling is not the requested observation behavior.

   Reference: Cisco Nexus 9000 Series NX-OS System Management Configuration Guide, Release 10.3(x) — Configuring the Embedded Event Manager — Action statements — default action note; Policies guidelines

10. 10A Nexus 9000 image transfer completes, but file corruption is suspected before an upgrade. Which check tests the downloaded file against Cisco's published image value?

    1. A. Compare the downloaded image’s filename and byte count with the download listing
    2. B. Calculate the downloaded image’s checksum twice and compare the two local results
    3. C. Calculate the image checksum and compare it with Cisco’s published matching digest
    4. D. Confirm that the image appears in the bootflash directory and has a nonzero size

    Answer: C

    Explanation: Cisco documents comparing the image "checksum" with its published value. Filenames, byte counts, and directory presence do not verify identical content. Recalculating the same corrupt file twice can agree without matching the trusted Cisco image.

    Reference: Cisco Nexus 9000 Series NX-OS Software Upgrade and Downgrade Guide, Release 10.3(x) — Upgrade NX-OS software — image checksum verification