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 file server has an incorrect default gateway configured.

  Why it's wrong here

  For devices to communicate within the same local subnet, a default gateway is not required because traffic can be directly forwarded using MAC addresses resolved via ARP. The problem states the user can ping the file server, implying they are on the same local network segment. An incorrect default gateway on the file server would only impact its ability to reach destinations outside its local subnet, such as the internet, but would not prevent local file-sharing connections or ICMP pings from a client on the same subnet.

  When this WOULD be correct

  A user on a different subnet cannot reach the file server, but can ping other external hosts. The file server's default gateway is misconfigured, preventing return traffic from routing back to the user's subnet.

• ✗

  The user's workstation has an incorrect DNS server configured.

  Why it's wrong here

  DNS (Domain Name System) is responsible for resolving human-readable hostnames into IP addresses. The problem implies the user is attempting to connect to the file server using its IP address, or at least that the connection failure is not due to name resolution. If the connection attempt uses a direct IP address, DNS is entirely bypassed. Therefore, an incorrect DNS server configuration on the user's workstation would only prevent access to resources by hostname, not by IP address, and would not explain the inability to connect to a file share via IP while still being able to ping it.

  When this WOULD be correct

  A user reports they can access the internet by IP address but cannot browse websites by domain name. The workstation has a static IP with an incorrect DNS server IP, preventing name resolution.

• ✓

  The file server's firewall is blocking the file-sharing protocol while allowing ICMP.

  Why this is correct

  The scenario describes successful internet access and successful ping to the file server, but failure to connect to an internal file share. This indicates that basic network connectivity (Layer 3) is present, as evidenced by ICMP (ping) working. However, the application-layer protocol for file sharing (e.g., SMB on TCP port 445 for Windows shares) is being blocked. A firewall on the file server itself is designed to filter traffic at higher layers, allowing specific protocols like ICMP while denying others, such as file-sharing protocols, thereby preventing the connection despite successful pings.

• ✗

  The user's workstation has a duplicate IP address assigned.

  Why it's wrong here

  A duplicate IP address on the user's workstation would lead to severe network instability and intermittent connectivity issues, often manifesting as complete loss of network access or frequent disconnections. When two devices on the same subnet claim the same IP, ARP conflicts occur, causing packets to be misrouted or dropped. Since the user can successfully ping the file server and access the internet, a duplicate IP address is highly improbable, as such a fundamental network conflict would prevent even basic ICMP communication.

  When this WOULD be correct

  A user reports intermittent connectivity and cannot access any network resources. The technician finds that the workstation's IP address conflicts with another device on the network, causing packet loss and disconnections.

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?”