🔧 Data Center Troubleshooting - CCTDC Practice Questions

Troubleshoot data center hardware and networking: UCS faults, Nexus interface issues, SAN connectivity problems, and using show commands.

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CCTDC DC Troubleshooting Question Bank (19 Questions)

Browse all 19 practice questions covering Data Center Troubleshooting for the CCTDC certification exam. Each question includes the full answer and a detailed explanation to help you understand the concepts.

  1. Question 1Cisco Data Center Troubleshooting

    Where should you look first when troubleshooting a Nexus switch issue?

    AThe internet
    BSystem logs ('show logging last <n>'), module status ('show module'), and interface status ('show interface status')✓
    CThe power supply LEDs only
    DThe running-config only
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    Nexus troubleshooting starts with: 'show logging last 50' (recent syslog events), 'show module' (line card status), 'show interface status' (port states), 'show system resources' (CPU/memory), and 'show environment' (hardware health).

  2. Question 2Cisco Data Center Troubleshooting

    A server cannot see its storage LUNs through the Fibre Channel SAN. What should be checked?

    ADNS resolution
    BFLOGI database (server registered?), zoning (server in zone with storage?), LUN masking (storage presenting LUN to server WWN?)✓
    CDHCP configuration
    DNTP synchronization
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    SAN LUN visibility troubleshooting: 1) 'show flogi database' — is the server HBA logged in? 2) 'show zone' — are server and storage in the same zone? 3) 'show fcns database' — is the storage target registered? 4) Check LUN masking on the storage array.

  3. Question 3Cisco Data Center Troubleshooting

    What is the most likely cause when a Nexus switch interface shows 'SFP not detected'?

    AIncorrect VLAN assignment
    BThe SFP module is not properly seated, unsupported, or failed✓
    COSPF misconfiguration
    DSpanning tree convergence
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    An undetected SFP typically indicates the module is improperly seated, incompatible (not on the supported list), or has physically failed. Reseat the SFP first, then try a known-good replacement.

  4. Question 4Cisco Data Center Troubleshooting

    What does 'show interface brief' display on a Nexus switch?

    ADetailed interface statistics
    BA summary of all interfaces showing status, IP address, speed, and VLAN assignment✓
    CRouting table
    DARP table
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    'show interface brief' provides a concise overview of all interfaces with their admin/operational status, IP addresses, speed/duplex, and VLAN membership.

  5. Question 5Cisco Data Center Troubleshooting

    What do input/output discards indicate on a Nexus switch interface?

    ANormal operation
    BFrames being dropped due to full queues, buffer exhaustion, QoS policy, or interface oversubscription✓
    CSuccessful transmission
    DInterface is disabled
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    Discards indicate packet drops: input discards = ingress buffer full, output discards = egress queue full (congestion). Check 'show interface counters detailed' for specific drop reasons. Causes: traffic bursts, microbursts, insufficient QoS buffering, or oversubscription.

  6. Question 6Cisco Data Center Troubleshooting

    What is the purpose of 'show logging' on a Nexus switch?

    ADisplay interface configurations
    BDisplay system log messages including errors, warnings, and informational events for troubleshooting✓
    CShow boot sequence
    DDisplay user accounts
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    'show logging' displays syslog messages including timestamps, severity levels, and descriptions of system events, hardware faults, and configuration changes for troubleshooting.

  7. Question 7Cisco Data Center Troubleshooting

    What does the FLOGI (Fabric Login) database show on a Cisco MDS switch?

    AVLAN assignments
    BAll devices (HBAs and storage ports) that have logged into the Fibre Channel fabric with their FCID and WWN✓
    CIP routing table
    DCPU utilization
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    'show flogi database' displays all devices connected to the SAN fabric: interface, VSAN, FCID (Fibre Channel ID), port WWN, and node WWN. If a server HBA doesn't appear in FLOGI, it hasn't successfully logged into the fabric — check cabling, zoning, or HBA status.

  8. Question 8Cisco Data Center Troubleshooting

    When should 'show tech-support' be collected on a Nexus switch?

    AOnly after a reboot
    BImmediately after a failure or issue occurs — before any remediation — to capture the state for TAC analysis✓
    COnly during scheduled maintenance
    DNever — it's too resource intensive
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    Collect 'show tech-support' immediately after an issue, BEFORE making changes — it captures the current state (logs, configs, counters, status). Redirect to file: 'show tech-support > bootflash:showtech_date.txt'. TAC requires this for case analysis.

  9. Question 9Cisco Data Center Troubleshooting

    Which NX-OS tool provides packet capture capability for troubleshooting on a Nexus switch?

    AWireshark
    BEthanalyzer✓
    Ctcpdump
    DSPAN only
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    Ethanalyzer is a built-in NX-OS packet capture tool (based on Wireshark/tshark) that captures packets on the management interface or in-band traffic for protocol troubleshooting.

  10. Question 10Troubleshooting

    How do you troubleshoot VXLAN tunnel issues on Nexus?

    Ashow ip route only
    BVerify underlay reachability (ping VTEP IPs), check 'show nve peers', 'show nve vni', and verify BGP EVPN adjacencies with 'show bgp l2vpn evpn summary'✓
    Cshow vlan brief
    Dshow spanning-tree
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    VXLAN troubleshooting: 1) Verify underlay routing (ping between VTEPs), 2) Check NVE interface (show nve peers/vni), 3) Verify BGP EVPN sessions (show bgp l2vpn evpn summary), 4) Check MAC/IP routes in EVPN tables.

  11. Question 11Cisco Data Center Troubleshooting

    Why might a port-channel on a Nexus switch show individual links as suspended?

    AThe switch is out of memory
    BLACP parameter mismatch, speed/duplex mismatch, or incompatible port-channel mode (static vs active/passive) between the two ends✓
    CThe cable is too long
    DThe power supply is failing
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    Suspended port-channel members: check LACP mode (active/passive) matches, speed/duplex settings are identical, port-channel mode is compatible, and 'channel-group' config matches on both sides. 'show port-channel summary' and 'show lacp neighbor' help diagnose.

  12. Question 12Cisco Data Center Troubleshooting

    What NX-OS command shows spanning tree topology information for a specific VLAN?

    Ashow vlan
    Bshow spanning-tree vlan <id> — displays root bridge, local bridge priority, port roles, and states✓
    Cshow route vlan
    Dshow interface vlan
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    'show spanning-tree vlan <id>' shows: root bridge ID/priority, local bridge priority, port roles (root/designated/alternate/backup), port states (forwarding/blocking), and costs. Essential for troubleshooting STP loops and convergence issues.

  13. Question 13Cisco Data Center Maintenance

    What is an EPLD (Electronic Programmable Logic Device) upgrade on a Nexus switch?

    AA software patch
    BA firmware update for the hardware logic chips (FPGAs) on line cards and supervisor modules, sometimes required alongside NX-OS upgrades✓
    CAn operating system reinstall
    DA configuration change
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    EPLD upgrades update firmware on FPGAs within line cards, supervisors, and other modules. Some NX-OS upgrades require matching EPLD versions. EPLD upgrades typically require module resets (not full switch reloads) and should be done during maintenance.

  14. Question 14Cisco Data Center Maintenance

    A Nexus switch shows a power supply as 'failed' in 'show environment power'. What is the recommended action?

    AImmediately reload the switch
    BReplace the failed PSU with an identical model while the switch is running✓
    CDowngrade NX-OS to fix the sensor
    DDisable redundancy mode
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    Nexus power supplies are hot-swappable. Replace the failed PSU with an identical model without shutting down the switch, as the remaining PSU(s) maintain power during replacement.

  15. Question 15Cisco Data Center Troubleshooting

    A Nexus switch FEX shows 'Offline' status. Which command helps diagnose the issue?

    Ashow vpc
    Bshow fex✓
    Cshow vlan
    Dshow ip route
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    'show fex' displays the status of all connected FEXes, including model, serial, online/offline state, and uplink port-channel status for diagnosing FEX connectivity issues.

  16. Question 16Cisco Data Center Troubleshooting

    A server connected to a Nexus switch via vPC is experiencing intermittent connectivity. Which log should be checked first?

    Ashow logging | include vpc✓
    Bshow tech-support
    Cshow environment
    Dshow ntp status
    Show Answer & Explanation
    Correct Answer: A
    Explanation:

    Checking logs filtered for vPC events reveals peer-link flaps, role changes, or member port state changes that could cause intermittent connectivity for hosts using vPC port-channels.

  17. Question 17Cisco Data Center Troubleshooting

    A Nexus switch shows high CPU utilization. Which command identifies the process consuming the most CPU?

    Ashow processes cpu sort✓
    Bshow logging
    Cshow interface counters
    Dshow vpc consistency
    Show Answer & Explanation
    Correct Answer: A
    Explanation:

    'show processes cpu sort' lists all running processes sorted by CPU utilization, quickly identifying the process responsible for high CPU and guiding further investigation.

  18. Question 18Cisco Data Center Troubleshooting

    What command shows environmental status (fans, power, temperature) on a Nexus switch?

    Ashow version
    Bshow environment✓
    Cshow interfaces
    Dshow running-config
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    'show environment' displays fan status/RPM, power supply status/wattage, and temperature sensor readings for monitoring hardware health on Nexus switches.

  19. Question 19Troubleshooting

    What is the purpose of 'show logging' on NX-OS?

    AShow interface logs
    BDisplay system log messages showing events, errors, warnings, and state changes for troubleshooting device issues✓
    CShow login history
    DShow configuration log
    Show Answer & Explanation
    Correct Answer: B
    Explanation:

    'show logging' displays syslog messages with timestamps, severity levels, and facility codes. Filter by severity or module to focus troubleshooting. Also check 'show logging logfile' for persisted messages.

Key DC Troubleshooting Concepts for CCTDC

troubleshootucs faultnexussanshowinterfacelog

CCTDC DC Troubleshooting Exam Tips

Data Center Troubleshooting questions in CCTDC are typically scenario-based. Focus on service-level decision making aligned to official exam objectives. Priority concepts: troubleshoot, ucs fault, nexus, san, show, interface.

What CCTDC Expects

  • Anchor your answer in select the most practical, secure, and scalable answer for the stated scenario.
  • DC Troubleshooting scenarios for CCTDC are frequently mapped to Domain 3 (35%), so read the objective carefully before picking controls or architecture.
  • Expect multi-service scenarios where DC Troubleshooting interacts with IAM, networking, storage, or observability patterns rather than appearing as an isolated service question.
  • When two options are both technically valid, prefer the choice that best aligns with the exam's operational scope (Entry) and managed-service best practices.

High-Value DC Troubleshooting Concepts

  • Know the core DC Troubleshooting building blocks cold: troubleshoot, ucs fault, nexus, san.
  • Review the edge-case features and limits for show, interface; these details are commonly used to differentiate answer choices.
  • Practice service-integration reasoning: how DC Troubleshooting pairs with DC Hardware, DC Networking in real deployment patterns.
  • For CCTDC, explain why the chosen DC Troubleshooting design meets reliability, security, and cost expectations better than the alternatives.

Common CCTDC Traps

  • Watch for answers that partially solve the requirement but miss operational constraints.
  • Questions in Troubleshooting often include distractors that look correct for DC Troubleshooting but violate least-privilege, durability, or availability requirements.
  • Avoid picking options purely by feature name; validate data path, failure handling, and governance impact before answering.
  • If the prompt hints at automation or repeatability, eliminate manual-only operational answers first.

Fast Review Checklist

  • Can you compare at least two DC Troubleshooting implementation paths and justify which one best fits the scenario?
  • Can you map the chosen answer back to Troubleshooting (35%) outcomes for CCTDC?
  • Can you explain security and access boundaries for DC Troubleshooting without relying on default-open assumptions?
  • Can you describe how DC Troubleshooting integrates with DC Hardware and DC Networking during failure, scaling, and monitoring events?

Exam Domains Covering DC Troubleshooting

Domain 3Troubleshooting35%

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