CompTIA Server+ Practice Test (SK0-005)

Passive QSFP+ direct-attach copper (DAC) cables are purpose-built for very short in-rack runs-typically 0.5 m to 5 m on passive twinax-and provide the full 40 Gbps data rate with almost no additional power draw or optical components. Active optical cables (AOC) and SR4 multimode fiber require integrated or external optics that add both cost and power, and they are designed for tens to hundreds of meters rather than a 2 m jumper. LR4 single-mode fiber is intended for long-haul links up to 10 km and is the most expensive option, making it inappropriate for an in-rack connection.

The 30-ampere, 250-volt NEMA L6-30P is a twist-locking ("L") plug designed for two-pole, three-wire 208/240 V circuits. It is rated for the full 30 A provided by the branch circuit and its locking design prevents the cord from being pulled out accidentally-exactly what is required for a rack PDU on a 208 V/30 A feed.

The straight-blade NEMA 5-15P is limited to 125 V/15 A and would neither meet the voltage nor current requirement. IEC 60320 C14 inlets are normally found on the equipment side of power cords and are rated at only 10 A, far below the circuit capacity. IEC 60320 C20 inlets support up to 16-20 A (depending on certification) but still fall short of the 30 A draw and offer no locking mechanism. Therefore, only the NEMA L6-30P satisfies both the electrical rating and the physical security needed.

The correct command is sudo vi /etc/ntp.conf. The sudo (superuser do) command is the standard and most secure method for executing a single command with elevated (root) privileges on a Linux system. It grants the necessary permissions for just that one command, adhering to the principle of least privilege. The su command would switch the user's entire shell to the root user, which provides more privilege than necessary for this single task. The runas command is a tool used on Windows operating systems to run a program as another user and is not applicable in a Linux environment. The chmod 777 /etc/ntp.conf command is a significant security risk; it would make the configuration file readable, writable, and executable by all users on the system, which is an insecure and improper way to manage system file permissions.

The correct action is to install the heaviest servers at the bottom of the rack and work upwards. This practice creates a low center of gravity, which is the most critical factor for ensuring the rack's stability and preventing it from becoming top-heavy and tipping over. While having assistance for lifting is an important personal safety measure, it does not address the stability of the rack itself. Confirming the floor's load capacity is a crucial planning step that should be completed before the installation begins, not during the physical act of mounting the servers. Placing servers in the middle does not create the lowest possible center of gravity and is not the recommended best practice for stability.

The correct answer is to install the 4U server, then the 2U server, and finally the two 1U servers. The fundamental principle of rack balancing for safety is to install the heaviest equipment at the bottom of the rack. This practice creates a low center of gravity, which minimizes the risk of the rack becoming top-heavy and tipping over, a significant safety hazard. In this scenario, the 4U database server is the heaviest component and must be installed first in the lowest available position. The next heaviest server, the 2U unit, should be installed above it, followed by the lightest 1U servers. The other installation orders are incorrect as they place lighter equipment below heavier equipment, raising the rack's center of gravity and making it dangerously unstable.

The correct answer is that the rail kit is not compatible with the specific server model. Server rail kits are frequently designed for specific models or generations of servers from a manufacturer, even within the same U-size. Differences in chassis dimensions, weight, and the precise location of mounting points necessitate a compatible rail kit for a secure and correct installation.

• A rail kit for a different U-size would also be incompatible, but the most specific and common issue is incompatibility with the server model itself, even when the U-size is correct. Therefore, the selected answer is the most likely cause.
• The scenario states that the outer rails were successfully attached to the rack posts, which rules out incompatibility with the rack's post type (threaded vs. square).
• It is highly improbable that a 2U server would be designed exclusively for 2-post racks due to its weight and depth; such servers almost always require the stability of a 4-post rack.

A full-height rack provides 42 rack units (RU). Add the space required by each item: GPU servers 6 × 4U = 24U; storage arrays 4 × 2U = 8U; KVM switch 1U; blanking panels 3U. Total consumed: 24 + 8 + 1 + 3 = 36U. Remaining capacity is 42U − 36U = 6U. The other options result from mis-adding one or more components or not subtracting from the rack's total height.

Best practice is to keep the rack's center of gravity low by mounting the heaviest devices-such as battery-based UPS modules-in the lowest available U positions. All equipment that cools front-to-back should have its intake facing the cold aisle so that hot exhaust is discharged only into the hot aisle. Lightweight devices such as top-of-rack switches can safely be placed at the upper front of the cabinet. The layout that places the UPS units in the bottom 8 U, all servers above them with their fronts toward the cold aisle, and the switch in the highest front position therefore meets both cooling and tip-over safety recommendations. The other options either put heavy equipment high in the rack, reverse server airflow into the cold aisle, or alternate orientations in ways that recirculate hot air and complicate cable management.

The array currently holds 9.6 TB of data (12 TB × 0.80). Over 18 months that amount will grow by (1.04)^18 ≈ 2.03, reaching roughly 19.5 TB. A RAID 6 array provides usable capacity equal to (N − 2) × 2 TB, so each extra 2 TB drive adds exactly 2 TB of usable space. To raise usable capacity from 12 TB to at least 19.5 TB requires ⌈(19.5 − 12) / 2⌉ = 4 additional drives, bringing the array to 12 disks and 20 TB of usable space. Adding two or three drives would leave less than 19.5 TB, and a wholesale replacement with larger disks costs more than the minimum solution.

For maximum availability the two power supplies must follow different electrical paths all the way back to separate utility feeds. Plugging one PSU into the PDU that is fed by UPS-A and the other into the PDU fed by UPS-B creates two independent (2N) power paths. If Utility #1, UPS-A, or PDU-A fails, the server continues to draw power through Utility #2, UPS-B, and PDU-B, meeting the SLA. The other options leave both PSUs on the same power chain or leave one supply unused; a single failure in that chain would still drop the server, so they do not meet the requirement.

Using one switched zero-U (vertical) PDU on circuit A and a second switched zero-U PDU on circuit B is the only design that satisfies every requirement. Zero-U PDUs mount on the rack's side rails, so they do not consume any rack units reserved for IT gear. A switched model supplies per-outlet metering and remote on/off control, meeting the NOC's manageability requirement. By feeding each server's two power supplies from different PDUs/circuits, the rack keeps running if either circuit fails, providing true path-level redundancy.

The other proposals fall short: basic horizontal PDUs lack remote switching and occupy valuable rack space; using two PDUs on the same circuit eliminates redundancy; and placing a static-transfer switch upstream still leaves only one horizontal PDU and loses 4 U of space, while also failing to offer per-outlet control.

The correct approach is to create two fully independent power paths, often referred to as an A/B power configuration. By connecting each of the server's power supplies to separate Power Distribution Units (PDUs), the configuration protects against a PDU failure. Ensuring each PDU is fed by an independent Uninterruptible Power Supply (UPS) on a separate electrical circuit protects against a UPS failure or a circuit breaker trip. This design eliminates any single point of failure in the power delivery system from the utility to the server. Connecting both power supplies to the same PDU or the same UPS creates a single point of failure, negating the benefit of having dual power supplies. Connecting one power supply to a non-UPS outlet removes the critical battery backup protection from that power path, exposing the server to data loss or downtime during a power outage.

The correct answer is a USB-to-serial adapter and a rollover (console) cable. This combination is the standard method for connecting a modern computer, which typically lacks a serial port, to the console port of a server or network device for direct command-line access. The USB-to-serial adapter provides the necessary serial interface via a USB port. The rollover cable, also known as a console cable, has a specific pinout designed to connect a terminal (the administrator's laptop) to the device's console port (often an RJ-45 connector).

• A crossover cable and an SFP+ transceiver are used for establishing a direct, high-speed Ethernet network connection between two devices, which is not applicable here since the server has no IP configuration and a console connection is required.
• A KVM switch and a VGA cable are used for managing a server via its local graphical interface (keyboard, video, mouse), not for the specific task of establishing a command-line session through a dedicated serial console port.
• A USB Type-C to Ethernet adapter and a patch cable would provide the administrator's laptop with a wired network connection but would not facilitate a direct serial console connection to the server.

Each caster will impose about 450 kg (≈1 000 lb) on the tile it touches (1 800 kg ÷ 4). That equals the panel's maximum static rating and leaves no safety margin. Placing the casters on a steel load-spreader plate or purpose-built equipment support platform bridges the load over two or more adjacent panels (and the underlying stringers or pedestals), cutting the point and static load seen by any one tile roughly in half and bringing the installation safely below the rating.

Swapping in a perforated airflow tile does nothing to increase the tile's load capacity. Bolting the rack through the access floor anchors it but still concentrates the full weight on the tiles (and can damage the raised-floor system). Loading heavier servers higher in the cabinet changes the centre of gravity but has no effect on the force each caster applies to the floor.

The correct answer is SC (Subscriber Connector). This connector is characterized by its square-shaped body and a simple push-pull locking mechanism, which directly matches the physical description provided in the scenario. LC (Lucent Connector) connectors are smaller, more rectangular, and feature a retaining latch. ST (Straight Tip) connectors are round and use a bayonet-style twist-lock mechanism. MPO (Multi-fiber Push On) connectors are rectangular and much larger, as they terminate multiple fibers in a single connector for high-density backbone connections.