Your FREE CompTIA Server+ Flashcards 2026 – 150+ Cards

Redundant Array of Independent Disks — combining multiple drives for performance, redundancy, or both.

A unit of vertical rack space equal to 1.75 inches (44.45 mm). A 2U server occupies two of these slots in a standard 19-inch rack.

A standalone server in an upright chassis like a desktop PC; good for small offices, but consumes floor space and doesn't rack-mount efficiently.

A server (e.g., 1U, 2U, 4U) that bolts into a standard 19-inch rack to maximize density in a data center.

A stripped-down server module that slides into a shared blade enclosure, which supplies common power, cooling, and networking to many blades.

The shared housing for blade servers; provides redundant power supplies, cooling, and backplane/network connectivity for all installed blades.

The physical size and shape of a server: tower, rack-mount (1U/2U/4U), or blade. Chosen for density, scalability, and the environment.

The connector on a motherboard that holds the processor; servers often have multiple sockets for multiprocessing.

Using two or more physical CPUs (multi-socket) so a server can execute more threads in parallel for heavy workloads.

Error-Correcting Code RAM that detects and corrects single-bit memory errors; standard in servers for data integrity.

RDIMM memory with a register between DRAM and the controller to improve stability with large amounts of RAM; common in servers.

Combining multiple network interface cards into one logical interface for higher bandwidth and/or failover redundancy.

Host Bus Adapter — a card that connects a server to storage (e.g., Fibre Channel or SAS), offloading I/O from the CPU.

Striping with no parity. Data is split across drives for speed and full capacity, but ANY drive failure loses all data (no fault tolerance).

Mirroring — identical copies on two drives. Survives one drive failure; usable capacity is half the raw total.

Striping with distributed single parity across 3+ drives. Survives one drive failure; capacity = (n − 1) drives.

Striping with double distributed parity across 4+ drives. Survives two simultaneous drive failures; capacity = (n − 2) drives.

A stripe of mirrors — combines RAID 1 redundancy with RAID 0 speed. Needs 4+ drives; high performance and fault tolerance.

A standby drive that automatically rebuilds a RAID array when a member drive fails, minimizing exposure time.

A component (drive, power supply, fan) that can be replaced while the server is powered on, with no downtime.

Just a Bunch Of Disks — drives presented individually with no RAID; no striping, mirroring, or parity.

Serial Attached SCSI — a fast, reliable enterprise drive/interface common in servers; supports dual-porting for redundancy.

Serial ATA — a lower-cost drive interface common for capacity-oriented or less performance-critical server storage.

Non-Volatile Memory Express — a high-speed protocol for SSDs over PCIe, offering far lower latency than SAS/SATA.

Direct-Attached Storage — storage connected directly to one server (internal disks or an external SAS enclosure).

Network-Attached Storage — file-level storage shared over the LAN using protocols like SMB/CIFS and NFS.

Storage Area Network — block-level storage over a dedicated high-speed network (Fibre Channel or iSCSI).

Internet Small Computer System Interface — block storage encapsulated in TCP/IP, letting a SAN run over standard Ethernet.

A second PSU so the server keeps running if one supply fails; often hot-swappable and on separate circuits.

Power Distribution Unit — distributes power to rack equipment; managed PDUs allow remote monitoring and per-outlet control.

Uninterruptible Power Supply — battery backup that bridges power loss and enables a graceful shutdown.

Baseboard Management Controller using IPMI — out-of-band hardware management for remote power, console, and sensor monitoring.

Managing a server over a dedicated channel (BMC/iLO/iDRAC) independent of the OS, even when the server is off or unresponsive.

Organizing power and data cables in a rack to maintain airflow, simplify service, and prevent accidental disconnects.

A data-center layout that alternates equipment rows so cold intake air and hot exhaust air are separated for efficient cooling.

Keyboard, Video, Mouse switch — lets one console control many servers; KVM-over-IP adds remote access.

Small Form-factor Pluggable transceivers that connect a switch/server port to fiber or copper; SFP+ supports 10 Gbps.

Quad Small Form-factor Pluggable transceiver for high-speed links (40/100 Gbps) using multiple lanes.

Fiber with a tiny core for long-distance, high-bandwidth runs using laser light; uses LC/SC connectors.

Fiber with a larger core for shorter, high-speed runs; cheaper optics than single-mode.

The 8-pin modular connector used for twisted-pair Ethernet (Cat 5e/6/6a) copper cabling.

Peripheral Component Interconnect Express — the high-speed expansion bus for NICs, HBAs, GPUs, and NVMe SSDs.

RDIMM memory with a register that improves stability with large RAM capacities; common in servers.

Dual In-line Memory Module — the physical RAM stick; servers favor ECC and registered variants.

Hardware (or firmware) that manages a RAID array, handling striping, mirroring, parity, and rebuilds.

Mounting hardware that lets a rack server slide in and out of the rack for installation and service.

Keyboard, Video, Mouse switch — lets one console control many servers; KVM-over-IP adds remote access.

Software that creates and runs virtual machines by abstracting physical hardware. Type 1 runs on bare metal; Type 2 runs on a host OS.

A bare-metal hypervisor that runs directly on hardware (e.g., ESXi, Hyper-V) for maximum performance; standard in production servers.

A hosted hypervisor that runs as an application on top of an OS (e.g., VirtualBox); used mainly for testing and labs.

A software-based computer with its own virtual CPU, memory, disk, and NIC, running on a hypervisor.

A lightweight, isolated package of an application and its dependencies that shares the host OS kernel; faster and smaller than a VM.

A point-in-time capture of a VM's state so you can roll back after a change; not a substitute for a real backup.

Physical-to-Virtual migration — converting a physical server into a virtual machine.

A primary function a server provides, such as file, print, web, database, DNS, DHCP, or directory services.

Dynamic Host Configuration Protocol — automatically assigns IP address, subnet mask, gateway, and DNS to clients.

Domain Name System — resolves hostnames to IP addresses; a core server role for name resolution.

A centralized identity store (e.g., Active Directory, LDAP) for authentication, authorization, and resource management.

Microsoft's directory service for managing users, computers, and policies via domains, organizational units, and Group Policy.

A Windows feature that centrally enforces configuration and security settings on users and computers in a domain.

The process of testing and applying OS and firmware updates on a schedule to fix bugs and close security holes.

Updating low-level device code (BIOS/UEFI, RAID controller, NIC) to fix issues or add support; test before applying in production.

A documented record of normal performance (CPU, memory, disk, network) used to detect abnormal behavior later.

Tracking CPU, memory, disk I/O, and network utilization over time to find bottlenecks and plan capacity.

Aggregated CPU and memory from hosts that can be allocated to VMs, often with reservations, limits, and shares.

Allocating more virtual RAM to VMs than the host physically has, relying on the fact that not all VMs peak at once.

Allocating storage on demand as data is written, so a volume can be presented larger than the space currently consumed.

Pre-allocating the full storage capacity up front, guaranteeing space at the cost of immediate consumption.

A flexible storage volume (e.g., via LVM) that can span disks and be resized without repartitioning physical drives.

The directory location where a filesystem or volume is attached and made accessible within the OS.

An account that exists only on a single server, used when domain authentication is unavailable or not appropriate.

A dedicated, often non-interactive account that runs an application or service; should use least privilege.

Using shell, PowerShell, or Bash scripts to automate repetitive administration consistently and at scale.

Maintaining diagrams, asset inventories, configuration records, and runbooks so the environment is understood and recoverable.

A formal process to request, review, approve, schedule, and document changes to reduce risk and outages.

Tracking hardware and software inventory, including warranties, licenses, and lifecycle, for the entire server estate.

Tracking and complying with software license terms (per-core, per-socket, per-user, or subscription) for servers and apps.

Network Time Protocol — synchronizes server clocks; accurate time is essential for logging, authentication, and certificates.

Managing a server from elsewhere via SSH (Linux), RDP (Windows), or web/console tools; secure the channel.

Secure Shell — an encrypted protocol (TCP 22) for remote command-line administration and secure file transfer.

Remote Desktop Protocol — Microsoft's protocol (TCP 3389) for graphical remote administration of Windows servers.

Designing systems with redundancy and failover so services keep running despite component failures.

Linking multiple servers to act as one system for high availability or load balancing; a failed node's load shifts to others.

Distributing client requests across multiple servers to improve performance and avoid overloading any single node.

Moving a running VM between hosts with little or no downtime (e.g., vMotion/Live Migration) for maintenance or balancing.

A software switch inside a hypervisor that connects VMs to each other and to physical networks.

Virtual network interface card presented to a VM by the hypervisor.

Creating a copy of a VM as a template or for rapid deployment of identical servers.

Moving a running VM between hosts with little or no downtime (vMotion / Live Migration).

A flexible volume that can span disks and be resized without repartitioning physical drives.

Lightweight Directory Access Protocol — the standard protocol for querying directory services.

Per-core, per-socket, per-user (CAL), or subscription terms that servers and apps must comply with.

A cluster where a surviving node takes over a failed node's workload to maintain availability.

Replication that confirms a write on both sites before acknowledging — zero data loss, higher latency.

Replication that acknowledges locally and copies later — faster, with a small potential data lag.

Forecasting future resource needs from trends so the server is scaled before it runs out.

Primary functions a server provides: file, print, web, database, DNS, DHCP, and directory services.

Confidentiality, Integrity, and Availability — the three core goals that guide all information security decisions.

Granting users and services only the minimum access required to do their job, limiting damage from compromise or error.

Assigning permissions to roles rather than individuals, then placing users into roles for consistent, manageable access.

Requiring two or more factors — something you know, have, or are — to authenticate, strongly reducing credential theft risk.

Reducing a server's attack surface by removing unused services/roles, closing ports, patching, and applying secure baselines.

Software on the server itself that filters inbound/outbound traffic by rules, complementing network firewalls.

Encrypting stored data (full-disk or volume encryption) so drives are unreadable if stolen or improperly disposed.

Protecting data moving over the network with TLS, IPsec, or SSH so it can't be read if intercepted.

Hardware Security Module — a tamper-resistant device that securely generates, stores, and uses cryptographic keys, and accelerates crypto.

Trusted Platform Module — a chip that stores keys and measurements to support secure boot and full-disk encryption (e.g., BitLocker).

A UEFI feature that verifies the bootloader and OS signatures so unauthorized or tampered code cannot load at startup.

Controlling physical access to servers with locked racks, badge entry, cameras, and mantraps to prevent tampering and theft.

Securely disposing of media by wiping, degaussing, or physical destruction (shredding) so data cannot be recovered.

A copy of data kept separately so it can be restored after loss, corruption, ransomware, or disaster.

A complete copy of all selected data; slowest to create and largest, but fastest and simplest to restore.

Backs up only data changed since the LAST backup (full or incremental); fast/small but restore needs the full plus every increment in order.

Backs up data changed since the last FULL backup; larger than incremental but restore needs only the full plus the latest differential.

A full backup assembled from a prior full plus subsequent incrementals, without re-reading all source data.

Keep 3 copies of data, on 2 different media types, with 1 copy offsite, to survive most failure and disaster scenarios.

Grandfather-Father-Son — a media rotation scheme using daily, weekly, and monthly sets for layered retention.

A snapshot captures point-in-time state on the same system (quick rollback); a true backup is a separate, restorable copy offsite.

Recovery Time Objective — the maximum acceptable time to restore a service after an outage.

Recovery Point Objective — the maximum acceptable amount of data loss, measured as time back to the last good backup.

Mean Time To Repair — the average time to fix a failed component and restore service.

Mean Time Between Failures — the average operating time between failures; a measure of reliability.

A documented, tested process for restoring IT services after a major disruption, defining roles, steps, RTO, and RPO.

A broader plan to keep the whole business operating during and after a disruption; DR is the IT subset of BCP.

A fully equipped, continuously updated alternate site that can take over almost immediately — the fastest, most expensive option.

A partially equipped alternate site with hardware and connectivity ready, needing data restore and some setup before takeover.

A basic facility (space, power, cooling) with no ready equipment; cheapest but slowest to bring online after a disaster.

Automatically switching to a redundant system or site when the primary fails, to maintain availability.

Returning operations to the primary system or site once it is repaired and verified after a failover.

Copying data to another system or site in real time or near-real time so a current copy is always available.

Periodically performing test restores to verify backups are complete, valid, and recoverable — an untested backup may not work.

A backup kept physically or logically disconnected from the network so ransomware and attackers cannot reach it.

Applying security updates promptly to close known vulnerabilities before they can be exploited.

Role-Based Access Control — assigning permissions to roles, then placing users into roles.

Destroying a drive's encryption key so the encrypted data becomes unrecoverable — fast sanitization.

Erasing magnetic media (HDD/tape) with a strong magnetic field; does not work on SSDs/flash.

Grandfather-Father-Son — a media rotation using daily, weekly, and monthly retention sets.

A plan to keep the whole business operating during a disruption; DR is its IT subset.

A documented, tested process to restore IT services after a disaster, defining roles, RTO, and RPO.

Multifactor authentication — requiring two or more factors to log in, blocking most credential theft.

NIST SP 800-88 methods of increasing assurance for removing data before media reuse or disposal.

Applying security updates promptly to close known vulnerabilities before exploitation.

A documented secure configuration that defines and maintains a server's expected state.

Copying data to another site in near-real time so a current recoverable copy always exists.

CompTIA's structured process: identify the problem, theorize a cause, test it, plan, implement/escalate, verify, and document.

The first step: gather information, question users, identify symptoms, and determine whether anything recently changed.

Step two: form a probable cause, questioning the obvious and considering multiple possibilities.

Step three: confirm or refute the suspected cause; if not confirmed, form a new theory or escalate.

After fixing, confirm the full system works and implement preventive measures before closing the issue.

The final step: record the cause, the solution, and lessons learned for future reference.

Power-On Self-Test — firmware diagnostics at boot; beep codes or POST codes indicate hardware faults like bad RAM or no video.

Audible POST signals whose pattern maps to a hardware fault (e.g., memory or video) per the vendor's reference.

A server that won't complete POST — check power, reseat RAM and cards, and look for shorts or a failed component.

The OS won't load — possible causes include a bad boot order, failed boot drive, corrupt bootloader, or degraded RAID array.

A fatal OS crash (Windows BSOD or Linux kernel panic) often caused by bad drivers, hardware faults, or corruption.

OS logs (Windows Event Viewer; Linux /var/log, journalctl) that record errors and warnings to diagnose problems.

A RAID array running with a failed member; still operational but unprotected — replace the drive and let it rebuild promptly.

The process of reconstructing data onto a replacement drive from parity or a mirror after a RAID member fails.

SMART errors, bad sectors, unusual noise, rising latency, or array degradation indicate a failing drive.

Self-Monitoring, Analysis and Reporting Technology — drive self-diagnostics that predict failures before they happen.

Excessive temperature from failed fans, blocked airflow, or dust; can cause throttling, shutdowns, or hardware damage.

An automatic power-off triggered when temperature exceeds safe limits, protecting components from damage.

Faulty RAM causing crashes or corruption; ECC logs and memory diagnostics help isolate the bad module.

No or poor network access — check cabling, link lights, NIC config, IP settings, VLAN, and switch port.

Tests reachability and round-trip time using ICMP; a basic first step for network connectivity problems.

Maps the per-hop path to a destination to find where traffic stops along the route.

Shows a server's IP address, subnet mask, and gateway; reveals misconfiguration or a missing DHCP lease.

Diagnoses DNS resolution; if you can ping by IP but not by name, suspect DNS.

A full disk or LUN causing failures; identify large files/logs, expand the volume, or archive data.

Sustained high processor use causing slowness — find the offending process, then tune, scale, or schedule the workload.

A process that fails to release RAM over time, eventually exhausting memory and degrading or crashing the server.

A failed service — check dependencies, configuration, permissions, ports in use, and the related event/log entries.

The single resource (CPU, memory, disk I/O, or network) limiting throughput; identified by comparing usage to the baseline.

Removing and firmly reinstalling a module (RAM, card, cable) to fix faults caused by a poor connection.

Excessive paging to disk when RAM is exhausted, causing severe slowdowns; add memory or reduce load.

Users can't log in — check the directory service, time sync (Kerberos), account lockouts, and password/policy issues.

A bad or loose data/power cable causing intermittent or no connectivity; test or replace and verify link.

A problem that started right after a change — review and, if needed, roll back the recent change first.

Handing an issue to someone with more access or expertise when a fix is beyond your scope or authority.

Numeric/LED codes a server displays during the Power-On Self-Test to indicate the failing stage.

A fatal OS crash (Windows BSOD or Linux kernel panic) usually from drivers, hardware faults, or corruption.

The Windows tool for reviewing system, application, and security logs to diagnose problems.

Linux logging — /var/log files and journalctl — used to investigate errors and service failures.

Excessive paging to disk when RAM is exhausted, causing severe slowdowns; add RAM or cut load.

Shows a server's IP, mask, and gateway; reveals misconfiguration or a missing DHCP lease.

A 169.254.x.x self-assigned address indicating the host couldn't reach a DHCP server.

When two link ends disagree on half/full duplex, causing collisions, errors, and poor throughput.