Network Troubleshooting & Diagnostics practice test: free CompTIA Network+ (N10-009) questions

Sample Practice Questions for Network Troubleshooting & Diagnostics

1. Question 1Ref: CompTIA Network+ N10-009 — Troubleshooting: Network Services Issues, 24%

   Users on VLAN 10 report intermittent connectivity while users on VLAN 20 are unaffected. The switch log shows frequent MAC address table changes on ports assigned to VLAN 10. What is the most likely cause?

   ADHCP scope exhaustionBSpanning tree topology changeCBroadcast stormDDuplicate IP addresses
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   Correct Answer
   B. Spanning tree topology change

   The keyed answer is "Spanning tree topology change". Frequent MAC table changes suggest STP topology reconvergence, which causes temporary connectivity loss. Broadcast storms affect all VLANs, DHCP exhaustion produces no-connectivity, and duplicate IPs cause specific host conflicts.

2. Question 2Ref: CompTIA Network+ N10-009 — Troubleshooting: Command Line Tools, 24%

   A technician uses the ping command and receives replies with a TTL value of 254. The destination is five hops away. What does the TTL value indicate about the packets?

   AThe packets have traversed one routerBThe packets are being fragmented at each hopCThe packets originated from a Linux hostDThe packets exceeded the hop limit
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   Correct Answer
   A. The packets have traversed one router

   The keyed answer is "The packets have traversed one router". TTL starts at 255 (or 128 on Windows) and decrements by one at each router hop. A TTL of 254 from a 255 starting point means one hop was traversed. TTL 0 would indicate the limit was exceeded.