N10-009 Network Implementation 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 IP address of the router interface must be in the same subnet as the management VLAN

  Why it's wrong here

  The IP address configured on a router's subinterface for a trunk link is assigned to a specific VLAN and acts as the default gateway for devices within that particular VLAN's subnet. While a management VLAN might exist, the router's trunk subinterface IP address does not inherently need to belong to that specific VLAN. It can be part of any VLAN that requires routing services, and multiple subinterfaces, each with an IP from a different VLAN subnet, can exist on the same physical trunk interface.

  When this WOULD be correct

  If the question asked about configuring the router interface for management access to the switch (e.g., telnet/SSH), then the router's IP must be in the same subnet as the management VLAN to reach the switch's management IP.

• ✗

  The subinterface encapsulation must match the switch's native VLAN default

  Why it's wrong here

  On a router, each subinterface configured for a trunk link uses the "encapsulation dot1Q <VLAN_ID>" command, where "<VLAN_ID>" explicitly specifies the VLAN tag that the subinterface will process. The native VLAN, by definition, carries untagged frames. Therefore, the encapsulation on a subinterface is tied to a specific tagged VLAN ID, not to the native VLAN's default, which is handled differently (either implicitly untagged or explicitly assigned to a subinterface with the "native" keyword).

  When this WOULD be correct

  If the question asked about ensuring the router subinterface uses the same VLAN ID as the switch's native VLAN for untagged traffic, then matching the native VLAN default would be correct. For example, if the switch's native VLAN is VLAN 1, the router subinterface must also be configured with native VLAN 1.

• ✓

  The native VLAN on the router subinterface must be consistent with the switch's native VLAN

  Why this is correct

  When configuring an 802.1Q trunk link between a switch and a router, the native VLAN configuration must be identical on both devices. The native VLAN carries untagged frames across the trunk, meaning these frames are not encapsulated with an 802.1Q tag. If the native VLANs differ, frames sent untagged by one device will be interpreted as belonging to a different VLAN by the other, leading to communication failures and potential security vulnerabilities where traffic might be misdirected or dropped.

• ✗

  The router must be configured with inter-VLAN routing static routes

  Why it's wrong here

  When a router is configured with subinterfaces on a trunk link, it directly connects to multiple VLANs, acting as the default gateway for each. This setup inherently provides inter-VLAN routing capabilities because the router has a directly connected route for each VLAN's subnet. Therefore, explicit static routes are not required for the router to route traffic between these directly connected VLANs; it automatically knows how to forward packets between them.

  When this WOULD be correct

  In a scenario where the router is not directly connected to the switch but is reachable via another router, static routes would be needed to direct traffic between VLANs across the network.

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?”