Free N10-009 CompTIA Updates

The correct answer is A. The TX/RX connection is transposed . In fiber optic networking, communication requires proper alignment of the transmit (TX) and receive (RX) strands between devices. If these are reversed (not crossed correctly), the devices cannot properly send and re ceive signals, resulting in no link light . This is a common issue when working with fiber connections and media converters.

The scenario confirms that cables are tested and functional, and all devices are powered on, which eliminates physical damage or power issues. Fiber cables can still pass basic continuity tests while being incorrectly connected (TX to TX and RX to RX instead of TX to RX), which prevents link establishment.

Option B is incorrect because duplex mismatch (such as half vs. full duplex) typically causes performance issues like collisions and slow throughput, not a complete loss of link light. Option C is ruled out because the cables were tested successfully. Option D refers to errors that occur after a link is established, not a condition preventing link initialization.

According to CompTIA Network+ objectives, proper fiber polarity (TX/RX alignment) is critical for link establishment, making this the most accurate cause.

A subinterface is a logical interface created on a single physical router interface that allows routing between VLANs (known as Router-on-a-Stick (ROAS)). This method is commonly used when only one physical router is available, allowing inter-VLAN communication without additional hardware.

•Why not the other options?

•VXLAN (B) – This is used for extending Layer 2 networks over a Layer 3 infrastructure, primarily in data centers. It does not directly enable inter-VLAN communication.

•Layer 3 switch (C) – A Layer 3 switch can route between VLANs, but the scenario states that purchasing additional hardware is not an option.

•VIR (D) – This is not a standard networking term in the context of VLAN communication.

Definition of Jumbo Frames:

Jumbo frames are Ethernet frames with more than 1500 bytes of payload, typically up to 9000 bytes. They are used to improve network performance by reducing the overhead caused by smaller frames.

Why Switches Support Jumbo Frames:

Switches are network devices designed to manage data packets and can be configured to support jumbo frames. This capability enhances throughput and efficiency, particularly in high-performance networks and data centers.

Incompatibility of Other Devices:

Access Point: Primarily handles wireless communications and does not typically support jumbo frames.

Bridge: Connects different network segments but usually operates at standard Ethernet frame sizes.

Hub: A simple network device that transmits packets to all ports without distinguishing between devices, incapable of handling jumbo frames.

Practical Application:

Enabling jumbo frames on switches helps in environments where large data transfers are common, such as in storage area networks (SANs) or large-scale virtualized environments.