N10-009 Network Troubleshooting Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  The computer's firewall is blocking outbound ICMP

  Why this is correct

  If a user can successfully ping the default gateway (an internal network device) but fails to ping an external IP address like 8.8.8.8, it strongly suggests a local issue on the user's machine. Many operating system firewalls, by default or through custom configuration, are set to block outbound Internet Control Message Protocol (ICMP) echo requests to external destinations, while still permitting internal network communication. This selective blocking prevents external pings from leaving the host, even if the network path to the gateway is clear.

• ✗

  The router is missing a default route to the internet

  Why it's wrong here

  A missing or incorrect default route on the network router would prevent all devices on the local network from reaching external destinations, as the router would not know where to forward traffic destined for networks outside its directly connected subnets. Since the problem statement indicates that other users can successfully ping external IPs, the router's routing table, including its default route to the internet, must be correctly configured and operational. This scenario points away from a shared network infrastructure problem.

  When this WOULD be correct

  If the question stated that no users on the subnet can ping external IPs, and the router's routing table shows no default route, then a missing default route would be the likely cause.

• ✗

  The DNS server is not resolving the hostname

  Why it's wrong here

  The problem statement explicitly mentions the user attempting to ping the IP address 8.8.8.8, which is Google's public DNS server. When an IP address is used directly as the target for a ping command, the Domain Name System (DNS) is not involved in the resolution process. DNS is only required when a hostname (e.g., "google.com") needs to be translated into an IP address. Therefore, DNS server issues are irrelevant to this specific troubleshooting scenario.

  When this WOULD be correct

  In a scenario where a user cannot ping a hostname (e.g., www.google.com) but can ping its IP address (e.g., 8.8.8.8), and other users can ping the hostname, the most likely cause is DNS server misconfiguration or failure.

• ✗

  The network cable is loose or faulty

  Why it's wrong here

  A loose or faulty network cable would typically manifest as a complete loss of physical layer connectivity or highly intermittent network access. If the user can successfully ping the default gateway, it confirms that the physical connection between the computer's Network Interface Card (NIC) and the local network switch or access point is stable and functional. Therefore, the integrity of the network cable is not the root cause of the inability to reach external IP addresses.

  When this WOULD be correct

  In a scenario where a user cannot ping any IP address (neither gateway nor external), and link lights are off or intermittent, a loose or faulty network cable would be the likely cause.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.

Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

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