CompTIA Updated N10-009 Exam Questions and Answers by malcolm

The correct answer is Power redundancy because the devices in the rack are equipped with dual power supplies, which are specifically designed to support redundant power sources. According to CompTIA Network+ (N10-009) objectives under high availability and physical infrastructure concepts, redundancy is a key strategy to eliminate single points of failure.

If only one PDU (Power Distribution Unit) is installed, both power supplies from each device may ultimately rely on the same power source. This creates a single point of failure—if the PDU fails or loses upstream power, all connected equipment will shut down despite having dual power supplies.

By installing a second PDU connected to a separate power circuit (and ideally a separate UPS or power feed), each power supply in the servers and switches can connect to different PDUs. If one PDU fails, the other continues delivering power, ensuring uninterrupted operation.

Option B (Failed PSU monitoring) is not the primary reason for adding another PDU. Option C (Surge protection) can be provided by a single PDU. Option D (Electricity conservation) is unrelated to redundancy design.

Therefore, adding a second PDU provides true power redundancy.

Out-of-band (OOB) managementallows administrators to manage devices remotely even if the primary network is down. This is especially useful when physical access to the server is not possible. OOB management often uses a separate management interface, ensuring access regardless of the server ' s operational state.

Band Steering: This technology enables wireless devices to connect to the most optimal frequency band (2.4 GHz or 5 GHz) by encouraging capable devices to switch to the less congested 5 GHz band. This improves overall network performance and prevents overcrowding on the 2.4 GHz band.

Wireless LAN controller (B): This manages multiple access points in a network but does not handle frequency optimization.

Directional antenna (C): This focuses the signal in a specific direction but does not affect frequency selection.

Autonomous access point (D): This operates independently but lacks advanced features like band steering.

Understanding Rack Size Determination:

The size of a rack for installation is determined by the dimensions of the equipment to be housed in it, primarily focusing on the depth and height of the devices.

Switch Depth:

Depth of Equipment: The depth of network switches and other rack-mounted devices directly influences the depth of the rack. If the equipment is deeper, a deeper rack is required to accommodate it.

Industry Standards: Most racks come in standard depths, but it is essential to match the depth of the rack to the deepest piece of equipment to ensure proper fit and airflow.

Server Height:

Height of Equipment: The height of servers and other devices is measured in rack units (U), where 1U equals 1.75 inches. The total height of all equipment determines the overall height requirement of the rack.

Rack Units: A rack ' s height is typically described in terms of the number of rack units it can accommodate, such as 42U, 48U, etc.

Why Other Options are Less Relevant:

KVM Size: While important for management, KVM (Keyboard, Video, Mouse) switches do not typically determine rack size.

Hard Drive Size: Individual hard drives are installed within servers or storage devices, not directly influencing rack dimensions.

Cooling Fan Speed: Fan speed affects cooling but not the physical size of the rack.

Outlet Amperage: Power requirements do not determine rack dimensions but rather the electrical infrastructure supporting the rack.