7. Glossary

Active Directory (AD) — Microsoft's directory service for Windows domain environments. Provides authentication, authorization, and Group Policy management. Requires DNS.

Active-Active Cluster — A cluster configuration where all nodes serve production traffic simultaneously, with load distribution across nodes.

Active-Passive Cluster — A cluster configuration where one node serves production traffic while the other stands by, ready to take over via automatic failover.

APIPA (Automatic Private IP Addressing) — Self-assigned address in the 169.254.0.0/16 range, assigned by Windows when DHCP is unreachable. Indicates DHCP failure. → Section 3.3.1

Asset Tag — An organization's internal identifier for a hardware asset, typically a barcode or RFID label affixed to the device.

Baseline — A documented snapshot of normal system performance (CPU, memory, disk, network) at a known-good state, used as a comparison reference during troubleshooting.

BIA (Business Impact Analysis) — Analysis that identifies which systems are most critical to business operations and quantifies the cost of their unavailability. Drives DR priority and RTO/RPO requirements.

BIOS (Basic Input/Output System) — Legacy firmware that initializes hardware at boot and provides a pre-OS environment. Limited to 2TB boot drives. Succeeded by UEFI.

Blade Enclosure — A chassis that houses multiple blade servers in a compact form factor, sharing power, cooling, and network connectivity infrastructure.

Bootloader Password — A password required before the OS loads, preventing access to single-user mode or recovery console without authentication.

CIFS (Common Internet File System) — A file-sharing protocol for Windows clients (also called SMB). Used by NAS devices to serve Windows shares. → Section 2.2.3

Clock Skew — A difference in system time between two servers. Kerberos authentication fails if clocks differ by more than 5 minutes. Remediated by NTP synchronization. → Section 5.4.1

Clustering — Two or more servers that present a single logical service, monitoring each other via heartbeat and providing automatic failover.

CMOS Battery — A small battery on the server motherboard that maintains BIOS settings and the real-time clock when the server is powered off. Failure causes date/time reset and BIOS setting loss. → Section 5.2.1

Cold Site — A disaster recovery facility with power and cooling but no hardware. Longest recovery time (days to weeks).

Compression — A storage efficiency technique that encodes redundant data patterns to reduce storage consumption. Adds CPU overhead during read/write operations.

Crash Cart — A portable cart with monitor, keyboard, and related equipment for local server access during emergencies or initial setup.

Deduplication — A storage efficiency technique that identifies and eliminates duplicate data blocks, storing only one copy and using references. Most effective on VMs and similar files. → Section 3.5.1

Default Gateway — The router address to which a server sends traffic destined for other networks. Misconfiguration prevents communication beyond the local subnet.

Degaussing — Destroying data on magnetic media by exposing it to a strong magnetic field. Destroys drive electronics as well. Does NOT work on SSDs.

DLP (Data Loss Prevention) — Systems that monitor and control data movement to prevent unauthorized exfiltration of sensitive data.

DNS (Domain Name System) — Protocol that translates hostnames (webserver01.corp.com) to IP addresses. Required for Active Directory and most application connectivity. → Section 3.3.2

ECC RAM (Error-Correcting Code) — Server memory that detects and corrects single-bit errors automatically. Standard in server environments to prevent silent data corruption.

ESD (Electrostatic Discharge) — Static electricity discharge that can silently damage semiconductor components. Prevented by grounding straps and anti-static work surfaces.

Failback — Returning services to the original active cluster node after it has been repaired. Can be manual or automatic; manual is safer.

Failover — The automatic transfer of services from a failed cluster node to the standby node, triggered by heartbeat loss.

Fibre Channel (FC) — A high-speed network protocol for SAN connectivity. Lower latency than iSCSI; requires dedicated FC switches and HBAs.

FCoE (Fibre Channel over Ethernet) — Fibre Channel traffic carried over 10GbE or faster Ethernet, reducing SAN infrastructure cost.

FQDN (Fully Qualified Domain Name) — A complete domain name specifying exact DNS hierarchy location (e.g., webserver01.corp.example.com).

FRU (Field Replaceable Unit) — A component designed to be replaced in the field without returning the entire system. Includes drives, PSUs, fans, and memory DIMMs.

GPT (GUID Partition Table) — Modern partition table standard supporting drives up to 9.4ZB, 128 partitions per disk, and required for UEFI boot.

Heartbeat — A dedicated network connection between cluster nodes used to monitor node health. Loss of heartbeat triggers failover. Should be on a separate network from production traffic.

HCL (Hardware Compatibility List) — Vendor-maintained list of components tested and approved for use with a specific server model. Non-HCL components risk incompatibility and void warranties.

HIDS (Host Intrusion Detection System) — Software that monitors a host for suspicious activity and alerts administrators. Detection only — does not block.

HIPS (Host Intrusion Prevention System) — Software that monitors a host for suspicious activity and actively blocks detected threats.

Hot Site — A disaster recovery facility that is a fully operational duplicate of production with replicated data and running systems. Fastest recovery (minutes to hours).

Hot-Swap — The ability to replace a component while the system is running without causing a failure. Applies only to components specifically rated for it (drives, PSUs, fans).

HBA (Host Bus Adapter) — An expansion card that connects a server to a SAN via Fibre Channel.

iDRAC (Integrated Dell Remote Access Controller) — Dell's out-of-band management interface. Provides remote console, power control, and hardware monitoring independent of the OS.

iLO (Integrated Lights Out) — HP/HPE's out-of-band management interface. Equivalent functionality to iDRAC.

IPMI (Intelligent Platform Management Interface) — A standard for out-of-band server management. Vendor-neutral; foundation for iDRAC and iLO.

iSCSI (Internet Small Computer Systems Interface) — A SAN protocol that carries SCSI commands over TCP/IP Ethernet networks. Lower cost than Fibre Channel; higher latency.

JBOD (Just a Bunch of Disks) — A storage configuration where drives are not combined into a RAID array; each drive is presented independently.

KVM (Keyboard-Video-Mouse) — A physical switch that allows one set of input/output devices to control multiple servers.

Kerberos — Authentication protocol used by Active Directory. Requires all parties to share a time source within 5 minutes (enforced via NTP).

LC (Lucent Connector) — A small form-factor fiber optic connector common in modern server and data center environments.

LUN (Logical Unit Number) — A logical reference to a storage volume presented by a SAN to a server.

LVM (Logical Volume Management) — A Linux storage abstraction layer allowing flexible volume management: Physical Volumes → Volume Groups → Logical Volumes.

Mantrap — A physical security control using two interlocked doors. The second door opens only after the first closes and the person is authenticated, preventing tailgating.

MBR (Master Boot Record) — Legacy partition table standard limited to 2TB drives and 4 primary partitions. Required for legacy BIOS boot.

MTBF (Mean Time Between Failure) — The average time between failures of a component or system. Higher MTBF = more reliable.

MTTR (Mean Time to Recover) — The average time required to repair and restore a failed component or system. Lower MTTR = better serviceability.

MFA (Multifactor Authentication) — Authentication requiring two or more factors from different categories: something you know, something you have, something you are. → Section 4.3.3

NAS (Network Attached Storage) — Network-accessible file storage that presents a file system to clients via NFS or CIFS/SMB. File-level access. → Section 2.2.3

NFS (Network File System) — A file-sharing protocol for Unix/Linux clients. Used by NAS devices to serve shares to Linux systems.

NIC Teaming — Combining multiple physical NICs into one logical interface for redundancy and/or increased throughput.

NTFS (New Technology File System) — Windows server file system. Supports ACLs, compression, encryption (EFS), journaling, and disk quotas.

NTP (Network Time Protocol) — Protocol for synchronizing system clocks. Critical for Kerberos authentication and accurate log timestamps.

OOB (Out-of-Band Management) — Server management that operates independently of the server's OS, via a dedicated management processor. Works even when the server is powered off or crashed.

P2V (Physical to Virtual) — Migration of a physical server into a virtual machine.

PCI DSS (Payment Card Industry Data Security Standard) — Compliance framework for any organization that stores, processes, or transmits payment card data.

PDU (Power Distribution Unit) — A device that distributes power within a rack from a single feed to multiple server power connections.

PII (Personally Identifiable Information) — Any information that can identify an individual (name, SSN, email, biometric data). Requires specific legal protections.

POST (Power-On Self-Test) — Hardware diagnostic routine that runs at boot to verify components. Failed POST indicates hardware initialization failure.

PSOD (Purple Screen of Death) — VMware ESXi hypervisor crash indicator. Equivalent to a BSOD but at the hypervisor level.

QSFP (Quad Small Form-Factor Pluggable) — A transceiver format supporting 40GbE and above.

RAID (Redundant Array of Independent Disks) — Technology combining multiple drives into a logical unit with varying degrees of performance and redundancy. → Section 2.2.2

RAS (Reliability, Availability, Serviceability) — The three pillars of server hardware design philosophy.

ReFS (Resilient File System) — A Windows Server file system with integrity checking, auto-repair, and large volume support. Suited for backup targets and Storage Spaces.

RFC 1918 — IETF standard defining private (non-routable) IPv4 address ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16.

RPO (Recovery Point Objective) — The maximum acceptable data loss measured in time. Drives backup frequency and replication strategy.

RTO (Recovery Time Objective) — The maximum acceptable downtime. Drives DR site type and failover automation.

SAN (Storage Area Network) — Network storage presenting raw block-level storage to servers via iSCSI or Fibre Channel. Block-level access; servers format the LUN themselves. → Section 2.2.3

SAS (Serial Attached SCSI) — Enterprise-grade storage interface. Faster and more reliable than SATA; backward-compatible with SATA drives.

SC (Standard Connector) — A square push-pull fiber optic connector, common in older data center installations.

SELinux (Security-Enhanced Linux) — A Linux mandatory access control system that applies per-process, per-file security policies independent of standard UNIX permissions.

SFP / SFP+ — Small form-factor pluggable transceivers. SFP supports 1GbE; SFP+ supports 10GbE.

SIEM (Security Information and Event Management) — Systems that aggregate and correlate security events from multiple sources to detect threats and enable investigation.

SLA (Service Level Agreement) — A contractual commitment to uptime, performance, and availability between a service provider and customer.

SMB (Server Message Block) — Windows file-sharing protocol. Also called CIFS. Used for Windows file server shares and NAS connectivity from Windows clients.

SSO (Single Sign-On) — Authentication architecture where one login provides access to multiple systems. Simplifies access and centralizes revocation.

Sysprep — A Windows tool that removes machine-specific information (SID, computer name, activation state) from an installation image before cloning or template deployment.

UEFI (Unified Extensible Firmware Interface) — Modern replacement for BIOS. Supports GPT partition tables, drives larger than 2TB for boot, Secure Boot, and faster boot times.

UPS (Uninterruptible Power Supply) — Battery backup device that provides temporary power during outages and protects against voltage irregularities.

VLAN (Virtual Local Area Network) — A logical network segmentation within a physical switch infrastructure. Traffic between VLANs requires a Layer 3 device (router or Layer 3 switch).

VMFS (VMware File System) — VMware's cluster-aware file system used for shared datastores in vSphere environments. Enables vMotion and vSphere HA by allowing simultaneous access from multiple ESXi hosts.

VBScript (VBS) — A legacy Microsoft scripting language largely replaced by PowerShell. Still tested on Server+ for historical awareness.

Warm Site — A disaster recovery facility with hardware installed but data requiring restoration. Recovery time: hours to days.

WWNN (World Wide Node Name) — A unique identifier for a Fibre Channel storage device (node-level).

WWPN (World Wide Port Name) — A unique identifier for each Fibre Channel port on a device. Used in FC zoning.

ZFS — A combined file system and volume manager for Linux/FreeBSD/Solaris. Features copy-on-write, built-in RAID, checksums, snapshots, and deduplication.