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 DHCP server is not authorized in Active Directory

  Why it's wrong here

  DHCP server authorization in Active Directory is a security feature in Windows environments designed to prevent unauthorized DHCP servers from issuing IP addresses on a domain network. If a DHCP server is not authorized, it will typically cease to issue leases or be ignored by domain clients, but it would not inherently prevent a client from attempting DHCP and subsequently falling back to APIPA due to a lack of *any* DHCP response. The core problem here is the DHCP server's inability to receive the client's request across subnets, not its authorization status.

  When this WOULD be correct

  This would be correct in a scenario where DHCP clients are on the same subnet as the DHCP server, the server is running Windows, and clients receive 'No DHCP server available' errors despite the server being operational. In that case, unauthorized DHCP server in AD would prevent it from leasing addresses.

• ✓

  The router does not have a DHCP relay (ip helper-address) configured

  Why this is correct

  Without a DHCP relay configured on the router, DHCP broadcast requests from clients cannot traverse different IP subnets or VLANs to reach a DHCP server located in another segment. The `ip helper-address` command (or equivalent) is essential for the router to convert these broadcasts into unicast packets and forward them to the specified DHCP server. Consequently, the client's DHCP discovery request never reaches the server, leading to a timeout and the assignment of an Automatic Private IP Addressing (APIPA) address.

• ✗

  The computer's NIC is faulty

  Why it's wrong here

  A faulty Network Interface Card (NIC) typically manifests as a complete lack of link connectivity, intermittent network access, or erratic packet loss. The consistent acquisition of an APIPA address, however, indicates that the NIC is functional enough to establish a physical link and attempt DHCP discovery. This behavior suggests the NIC itself is working correctly at Layer 1 and Layer 2, but the DHCP process is failing at a higher layer or due to network configuration issues.

  When this WOULD be correct

  A technician finds a computer with no network connectivity and no IP address (or a 169.254.x.x address) after replacing the NIC. The switch port shows link but the computer cannot obtain an IP address even after static configuration fails. In that scenario, a faulty NIC would be the likely cause.

• ✗

  The switch port is in the wrong VLAN

  Why it's wrong here

  If the switch port were in the wrong VLAN, the client's DHCP requests would be broadcast into an incorrect network segment, preventing them from reaching the intended DHCP server. While this would certainly result in no network access and potentially an APIPA address, the problem statement indicates the technician already confirmed the port is in the correct VLAN. Therefore, the issue lies not with the client's initial VLAN assignment, but with the DHCP server's reachability across VLAN boundaries.

  When this WOULD be correct

  A technician sees a computer with an IP address from a different subnet than expected (e.g., 192.168.1.x instead of 10.0.0.x) and the switch port is configured for a different VLAN than the one the computer is physically connected to. In that case, the wrong VLAN assignment would cause the incorrect IP address.

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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