CompTIA Server+ (SK0-005) flashcards

The process of irreversibly destroying or altering data on storage media to make it unrecoverable by any means.

• Crucial for protecting sensitive information.
• Methods include overwriting, degaussing, and physical destruction.
• Compliance with regulations (e.g., GDPR, HIPAA) often requires specific sanitization levels.

Memory trick: Sanitization wipes the slate clean, ensuring data never returns.

A rack unit (U) equals 1.75 inches of vertical rack space; server and equipment heights are measured in U to determine rack capacity.

• 1U = 1.75 inches (4.45 cm)
• Standard racks are commonly 42U in height
• Available space = total U minus U already occupied

Memory trick: Each U is a 1.75-inch slice of the rack sandwich.

Incorrect settings on a client machine that prevent it from properly resolving hostnames to IP addresses, often leading to connectivity issues when using hostnames.

• Symptoms include successful IP-based connectivity but failed hostname-based connectivity.
• Can be caused by incorrect DNS server addresses, firewall rules blocking DNS traffic, or issues with local host files.
• Troubleshooting involves checking `ipconfig /all` (Windows) or `cat /etc/resolv.conf` (Linux) and testing DNS servers.

Memory trick: Don't Name Servers, Just Say IP!

Incorrectly configured default gateway IP address on a server, preventing or intermittently disrupting communication with hosts outside its local subnet.

• Symptoms include successful internal network communication but failed or intermittent external communication.
• The default gateway is the exit point for traffic leaving the local network segment.
• Troubleshooting involves checking `ipconfig` (Windows) or `ip route` (Linux) and pinging the gateway IP.

Memory trick: Gateway is the 'Exit Door' to the world!

A security principle that requires users, programs, and processes to be granted only the minimum necessary permissions to perform their authorized functions.

• Minimizes potential damage from errors or malicious acts.
• Reduces the attack surface.
• A fundamental concept in access control.

Memory trick: Only give what's needed, no more, no less.

A communication interface and protocol developed specifically for SSDs to take advantage of their high speeds, connecting directly to the PCIe bus.

• Utilizes PCIe lanes for direct CPU access.
• Offers significantly lower latency and higher throughput than SATA or SAS.
• Ideal for high-performance applications like databases and virtualization.

Memory trick: NVMe is the Nitro for your Virtual Memory Express.

A kernel parameter (`vm.swappiness`) in Linux that controls the tendency of the kernel to move processes out of physical memory and into swap space. A higher value (0-100) means more aggressive swapping.

• Default value is often 60 on many distributions.
• Lowering `swappiness` (e.g., to 10 or 0 for databases) can improve performance by keeping more data in physical RAM.
• Excessive swapping, even with free RAM, points to a high `swappiness` value.
• Checked with `cat /proc/sys/vm/swappiness` and set with `sysctl -w vm.swappiness=X`.

Memory trick: Swappiness too high? Your RAM is lazy, making disk do all the work!

Containerization is a lightweight virtualization technology that packages an application and all its dependencies (libraries, binaries, configuration files) into a single, isolated unit called a container.

• Provides process-level isolation, not full OS isolation like VMs.
• Ensures application portability and reproducibility across environments.
• Offers faster startup times and lower resource overhead than VMs.

Memory trick: Containers Isolate Apps, Portability is Key.

The process of reducing or eliminating an unwanted magnetic field, used to destroy data on magnetic storage media.

• Uses a powerful magnetic field.
• Renders data unrecoverable on HDDs and tapes.
• Makes the drive unusable afterwards.

Memory trick: Destroy Data: Don't just delete, DEGAUSS!

A command-line utility for securely copying files between local and remote hosts using the SSH protocol.

• Encrypts data in transit.
• Authenticates using SSH credentials (passwords or keys).
• Simple syntax for file and directory transfers.

Memory trick: Secure Copy (SCP) for Sensitive Content.

A disaster recovery site that has essential hardware and infrastructure in place, but requires loading of data and applications to become fully operational.

• Lower cost than a hot site, higher than a cold site.
• Recovery Time Objective (RTO) typically hours to days.
• Recovery Point Objective (RPO) depends on backup frequency.

Memory trick: DR Sites: Hot, Warm, Cold – like your coffee!

Investigating network devices (routers, firewalls, load balancers) positioned between a server and external clients when local connectivity works but external connectivity fails despite the server's local firewall being open.

• Commonly involves checking port forwarding, NAT rules, and Access Control Lists (ACLs).
• External connectivity issues often originate outside the server itself.
• Tools include `traceroute`/`tracert` to identify network path and firewall/router management interfaces.

Memory trick: External access blocked? Think outside the server!

SOPs are detailed, step-by-step instructions compiled by an organization to help workers carry out routine operations. They aim to achieve efficiency, quality output, and uniformity of performance.

• Ensures consistency and reduces errors in repetitive tasks.
• Facilitates training and knowledge transfer.
• Critical for compliance with security and operational standards.

Memory trick: SOPs Standardize Operations Perfectly.

A software framework that provides an environment for running and managing enterprise applications, often handling business logic and dynamic content generation.

• Executes business logic.
• Interacts with web servers and database servers.
• Generates dynamic content for clients.

Memory trick: Application servers are the brains, not just the face or memory.

A backup rotation scheme that uses daily (Son), weekly (Father), and monthly/yearly (Grandfather) backups to provide varying retention periods and recovery points.

• Balances storage space with recovery capability.
• Provides multiple generations of backups.
• Widely used for tape and disk-based backup strategies.

Memory trick: Backup Rotation: GFS is the 'Grand' standard for generations!

A type of memory module used in servers that includes a register to buffer electrical loads, allowing for higher memory capacities and improved stability.

• Stabilizes electrical signals
• Enables higher total memory capacity
• Common in enterprise servers

Memory trick: RDIMM's registered, UDIMM is straight, LRDIMM loads spread, ECC keeps data great.

A backup type that copies all data that has changed since the most recent full backup. Each differential backup builds upon the last full backup.

• Requires the last full backup and the latest differential to restore.
• Faster to restore than incrementals (fewer tapes).
• Takes more space than incremental backups over time.

Memory trick: Differential builds on the Full, Incremental just on the last.

cron is a time-based job scheduler in Unix-like computer operating systems. Users who wish to maintain their own regularly scheduled jobs use crontab (cron table) files.

• Used for scheduling recurring tasks
• Jobs defined in crontab files
• Syntax specifies minute, hour, day of month, month, day of week

Memory trick: Linux tasks: `cron` runs on time, `at` runs just once!

A data replication method where data is written to both the primary and secondary storage systems simultaneously, ensuring zero data loss (RPO = 0) at the expense of potential latency.

• Guarantees RPO = 0 (zero data loss).
• Primary system waits for confirmation from secondary.
• Introduces latency, typically used over short distances.

Memory trick: Sync is instant copy, Async is delayed copy.

A high-density SAS connector that bundles four SAS lanes into one cable, commonly used to connect HBAs/RAID controllers to backplanes or JBOD enclosures.

• SFF-8087 = internal mini-SAS, 4 lanes per cable
• SFF-8088 is the external equivalent connector
• SFF-8482 connects a single SAS/SATA drive directly

Memory trick: Mini-SAS bundles four lanes like a four-lane highway squeezed into one cable.

A virtual disk provisioning type where the full disk space is allocated immediately, but blocks are zeroed out only when they are first written to by the guest OS.

• Consumes full space immediately.
• Zeroing on first write can cause performance spikes.
• Different from 'eager zeroed' (zeroed at creation) or 'thin provisioned' (grows as needed).

Memory trick: Lazy zeroing makes for slow starts.

A characteristic of a system, which aims to ensure an agreed level of operational performance for a higher than normal period.

• Minimizes downtime.
• Achieved through redundancy, failover, clustering.
• Eliminates single points of failure.

Memory trick: HA keeps things Always Up.

A backup rotation scheme that uses three generations of backups: daily (Son), weekly (Father), and monthly/yearly (Grandfather), each with increasingly longer retention periods.

• Optimizes storage and recovery times.
• Provides multiple recovery points over different timescales.
• Commonly used for long-term data retention.

Memory trick: GFS: Grandparents for years, Parents for weeks, Kids for days.

When a drive fails in a RAID 5 array, the array enters a degraded state, continuing to function but with significantly reduced performance due to on-the-fly data reconstruction.

• RAID 5 can tolerate a single drive failure.
• Performance degrades substantially when in a degraded state.
• High disk I/O with normal CPU/memory often points to degraded RAID.

Memory trick: When the disk is maxed but CPU is chill, suspect a degraded RAID making it ill.

Measures taken to protect server hardware from unauthorized physical access, damage, or theft.

• Includes server room access controls, rack security, and environmental controls.
• Aims to prevent tampering, theft, and environmental harm.
• Often multi-layered, combining various techniques.

Memory trick: Server Security: Layer it up, from room to rack!

A golden image, or VM template, is a pre-configured virtual machine disk image that includes an operating system, applications, and configurations, used as a master copy for deploying multiple identical VMs.

• Ensures consistency and standardization
• Accelerates VM deployment
• Reduces manual configuration errors

Memory trick: VM deployment: Clone the gold, avoid the toil!

A data center cooling strategy that physically encloses the hot aisles, preventing hot exhaust air from mixing with cold intake air and improving cooling efficiency.

• Isolates hot air
• Increases CRAC efficiency
• Reduces hot spots and recirculation

Memory trick: Containment keeps air apart, raised floors give a start, liquid cools where heat is high, CRAC units never lie.

A critical system event in Windows indicating that the system has rebooted without cleanly shutting down, often due to an unexpected power loss or system unresponsiveness.

• Points to an abrupt interruption of the power supply or a complete system hang.
• Common causes include power outages, faulty power supplies (less likely with redundant working ones), loose power cables, or overloaded circuits.
• Troubleshooting involves checking physical power connections, power sources, and potentially stress-testing components if a system hang is suspected.

Memory trick: Event 41: Power's Gone! No graceful goodbye for the server.

A dedicated storage device connected to a network that allows authorized network users and heterogeneous clients to store and retrieve data from a centralized location. Many modern NAS devices also support iSCSI targets for block-level access.

• Provides file-level access (SMB, NFS).
• Often supports block-level access via iSCSI targets.
• Leverages existing network infrastructure (Ethernet).
• Cost-effective and easy to manage for small to medium environments.

Memory trick: NAS is the 'Network All-in-one Storage' for small offices.

The Linux Out of Memory (OOM) Killer is a kernel mechanism that terminates processes to free up memory when the system runs out of both physical RAM and swap space.

• Activates under extreme memory pressure.
• Prevents system from crashing due to memory exhaustion.
• Indicates a severe memory resource problem.

Memory trick: OOM Killer means memory's empty.

A server form factor designed to be installed into a standard 19-inch server rack, secured by screws or tool-less rails.

• Fits standard rack units (U)
• Optimized for high-density environments
• Often requires specific rail kits for installation

Memory trick: Racks hold servers, Blades go in a case, Towers stand alone, Mini-ITX is a base.

A high-level, interpreted programming language widely used in server administration for automation, data processing, and system integration due to its simplicity, readability, and extensive libraries.

• Easy to learn and read.
• Rich standard library for system tasks.
• Cross-platform compatibility.

Memory trick: Python Powers Practical Programs

A backup type that copies only data that has changed since the last full or incremental backup.

• Smallest daily backup size
• Fastest daily backup time
• Restoration requires the last full backup and all subsequent incremental backups

Memory trick: Incremental: It's all about the 'next step' changes.

The process of copying data in real-time or near real-time between two or more storage systems to maintain data consistency and availability.

• Can be synchronous (real-time) or asynchronous (near real-time).
• Essential for disaster recovery and high availability.
• Often used in conjunction with clustering or failover mechanisms.

Memory trick: Replication: It's a 'replica' for seamless takeover!

A secure version of HTTP that uses SSL/TLS to encrypt communication between a web browser and a server.

• Encrypts data in transit.
• Uses port 443 by default.
• Provides authentication and data integrity.

Memory trick: For web traffic, 'S' stands for Secure.

UPS capacity is rated in VA (volt-amps); actual wattage divided by the power factor gives the required VA rating needed to support a load.

• VA = Watts / Power Factor
• Power factor for IT loads is often around 0.9
• Always round up to the next standard UPS VA rating

Memory trick: Divide watts by the power factor to reveal the true VA giant hiding underneath.

iSCSI encapsulates SCSI commands over TCP/IP, allowing block storage to be shared over standard Ethernet networks using TCP port 3260.

• Default iSCSI port: TCP 3260
• iSCSI provides block-level storage over IP networks
• Requires initiator (client) and target (storage) configuration

Memory trick: iSCSI knocks on door 3260 to deliver its block of storage.

A warning from a drive's Self-Monitoring, Analysis, and Reporting Technology (SMART) that indicates an increased likelihood of imminent drive failure, even if the drive is currently functional.

• Allows for proactive replacement to prevent actual data loss or performance degradation.
• Commonly reported by hardware RAID controllers or OS utilities.
• Hot-swapping is often possible for enterprise drives in RAID arrays.
• Ignoring these warnings significantly increases risk.

Memory trick: Predicted failure? Replace it before the crystal ball shatters!

Physical security measures applied directly to server racks or cabinets to restrict unauthorized access to the servers and equipment contained within them.

• Adds a layer of security inside a secured room.
• Includes locking cabinets, smart racks, and individual bay locks.
• Protects against insider threats and unauthorized tampering.

Memory trick: Think of nested security: Perimeter, Room, then Rack.

Thermal paste (or thermal grease) is a compound applied between a CPU/chipset and its heatsink to improve heat transfer by filling microscopic air gaps. Over time, it can dry out and degrade, losing its thermal conductivity.

• Crucial for efficient heat transfer from components to heatsinks.
• Degrades over time, becoming dry and less effective.
• Leads to higher component temperatures, even with adequate cooling fans.
• Replacement is a common maintenance task for overheating issues.

Memory trick: Think of a server's heat like a campfire: too much heat, not enough escape routes.

The process of rendering data storage media unusable and the data irrecoverable through mechanical or chemical means.

• Ensures data cannot be retrieved.
• Often involves shredding, pulverizing, or incineration.
• Required for highly sensitive data on retired hardware.

Memory trick: Destroy it all, so no one can recall.

A component used to fill unused rack unit spaces in a server rack, preventing hot air recirculation and improving cooling efficiency by directing airflow.

• Fills empty rack U spaces
• Prevents hot/cold air mixing
• Improves cooling efficiency

Memory trick: Blanking panels block, cables manage the flock, side panels cover, front doors discover.

A Windows stop code indicating a severe, unrecoverable hardware error detected by the Windows Hardware Error Architecture.

• Often points to CPU or motherboard issues.
• Can be related to overclocking, voltage, overheating, or faulty hardware.
• Requires thorough hardware diagnostics.

Memory trick: 124 on the floor, CPU's sore, hardware's core!

A high-speed network technology primarily used for connecting computer data storage to servers in storage area networks (SANs), offering dedicated, low-latency, block-level data transfer.

• Dedicated network for storage traffic.
• Provides block-level access to storage.
• Known for high throughput and extremely low latency.
• Requires specialized Host Bus Adapters (HBAs) and switches.

Memory trick: FC is the 'Fastest Connection' for SAN.

A malfunction of a server's internal cooling components, most commonly fans, leading to localized overheating of critical hardware like CPUs, memory, or GPUs.

• Often indicated by high temperatures reported by internal sensors.
• Can occur even when ambient data center temperatures are normal.
• Requires immediate attention to prevent hardware damage or thermal throttling.

Memory trick: If it's 'Hot Inside', check the 'Fans'.

Error 1053 indicates that a Windows service failed to respond to the Service Control Manager's start or control request within the configured timeout period.

• Often points to issues with the service executable itself.
• Can be caused by corruption, missing dependencies, or internal errors.
• Requires checking application event logs for more specific errors.

Memory trick: 1053: Service is slow, or it just won't go.

Network segmentation divides a network into smaller, isolated segments, and firewall rules control traffic flow between these segments based on protocols, ports, and IP addresses.

• Enhances security by limiting the spread of breaches.
• Applies the principle of least privilege to network access.
• Requires careful planning to avoid disrupting legitimate traffic.

Memory trick: Firewall Rules Control Connections Safely.

A phased patching strategy involves deploying patches in stages, typically starting with non-production environments, then to non-critical production systems, and finally to critical production systems, to mitigate risks and ensure stability.

• Reduces risk of production downtime
• Allows for thorough testing of patches
• Balances security needs with stability requirements

Memory trick: Patching: Test, then roll, to keep the servers whole!

On Debian-based Linux systems, persistent network interface settings (IP address, subnet, gateway, DNS) are primarily configured in the '/etc/network/interfaces' file.

• File: /etc/network/interfaces.
• Manages static and dynamic IP settings.
• Processed at boot by ifup/ifdown.

Memory trick: Interfaces for IP Identity

A software application that controls network traffic to and from a single server or workstation.

• Operates at the host level, not the network perimeter.
• Provides granular control over ports, protocols, and applications.
• Essential for 'defense in depth' strategies.

Memory trick: Firewall shields the server, allowing only essential traffic through its gates.

A subnet mask defines the boundary between the network portion and the host portion of an IP address. An incorrect subnet mask can cause local and remote communication failures by misidentifying network boundaries.

• Determines local vs. remote addresses
• Incorrect mask leads to incorrect routing
• A /16 mask on a /24 network makes the local network appear larger

Memory trick: Subnet masks: the invisible fence of your network!

A networking feature that allows a single network interface controller (NIC) to be assigned multiple IP addresses, enabling a host to be reachable via different addresses.

• Uses one physical NIC for multiple IP addresses.
• Commonly used for hosting multiple websites/services on one server.
• Configuration typically involves creating virtual interfaces or sub-interfaces.

Memory trick: Alias IPs, Always Persistent

Internal DNS resolution relies on correctly configured DNS server entries that can resolve hostnames within a private network, often using specific internal DNS servers.

• External domains resolved by public DNS servers.
• Internal hostnames resolved by private/internal DNS servers.
• '/etc/resolv.conf' on Linux specifies DNS servers.
• Problematic if internal DNS server is missing or unreachable.

Memory trick: Linux networking is like a well-oiled machine, but DNS is the address book.

Hardware RAID controllers manage physical drives to present logical volumes to the operating system; these logical volumes must be created and initialized in the controller's utility before OS installation.

• OS sees logical volumes, not physical drives, with hardware RAID.
• RAID array must be configured in the controller's BIOS/utility.
• Unconfigured RAID means no storage for OS installation.

Memory trick: If the installer can't see the disk, check if your RAID took a risk.

A server power architecture designed to eliminate single points of failure in the electrical supply chain, typically involving dual power supplies in servers, dual PDUs, dual UPS units, and sometimes dual electrical circuits.

• N+1 or N+N redundancy at every stage (server PSUs, PDUs, UPS, circuits).
• Prevents downtime from component failure or planned maintenance.
• Requires careful planning and cabling to ensure true separation.

Memory trick: Redundant Power is 'Double Everything' from the wall to the server.

A warning from a drive's Self-Monitoring, Analysis, and Reporting Technology (SMART) data indicating an impending hardware failure, allowing for proactive replacement.

• Indicates a drive is likely to fail soon.
• Allows for proactive replacement without downtime.
• SMART data provides early warning signs.

Memory trick: Predictive failure means act fast, replace the drive before it's past.

The process of migrating an existing physical server into a virtual machine image.

• Preserves the original OS, applications, and data.
• Reduces downtime during migration.
• Commonly used when consolidating physical servers.

Memory trick: P2V moves the whole physical box, containers pack just the apps.

An error encountered when attempting to connect via RDP, indicating that the target server's Remote Desktop service is not running, is disabled, or not installed.

• Implies network connectivity to the server exists.
• Requires the 'Remote Desktop Services' role/feature to be installed.
• The 'Remote Desktop Services' service must be running and configured.

Memory trick: RDP no show? Service down, or config's a no go!

Memory thrashing occurs when a system frequently moves data between RAM and the page file (swap space) due to insufficient physical memory for active processes.

• Causes severe disk I/O bottlenecks.
• Results in significant performance degradation.
• Indicated by high paging activity and low virtual memory alerts.

Memory trick: Thrashing disk, system's a snail, memory's on trial.

The phase of incident response focused on stopping the spread of an attack, limiting its impact, and preventing further damage to systems and data.

• Follows the identification phase.
• Involves isolating affected systems, segmenting networks.
• Aims to prevent escalation and further compromise.

Memory trick: Prepare, Identify, Contain, Eradicate, Recover, Lessons.