SK0-006 — CompTIA Server+ V6 Cheat Sheet

Last revised: September 16, 2026

Cheat sheet: exam-prep reference for CompTIA Server+ V6 (SK0-006): server hardware, storage, networking, administration, security, disaster recovery, and troubleshooting.

Use the tables for a quick pre-exam check. Expand a topic’s notes for explanations, examples, and additional distinctions.

Scope and study context

Focus your review on these exam behaviors:

Identify the best server component, storage design, network service, or security control for a scenario.
Distinguish redundancy, backup, clustering, replication, and disaster recovery.
Troubleshoot from symptoms using logs, metrics, hardware indicators, and change history.
Apply least privilege, secure configuration, patching, monitoring, and documentation practices.
Recognize when a technology is used, not just what it is called.

This page is IT Mastery review support. It is not affiliated with CompTIA. The goal is to help you connect core server administration knowledge to original practice questions and exam-style decision making.

Scan the tables first. Identify weak areas: RAID, networking, server hardening, virtualization, backups, and troubleshooting.
Turn each weak area into topic drills. Do not only reread notes; answer questions until you can explain why wrong options are wrong.
Use detailed explanations. For SK0-006, the explanation is often more valuable than the answer because many questions test tradeoffs.
Finish with mixed mock exams. Server issues rarely stay in one topic. A storage failure may involve RAID, logs, firmware, backups, and business continuity.

Server Hardware Reference

Server Form Factors and Use Cases

Form factor	Best fit	Strengths	Watch for
Tower server	Small office, branch, non-rack environment	Simple deployment, less rack dependency	Less dense, may lack redundant infrastructure
Rack server	Data center, server room, standardized deployment	Scalable, good cable/power organization	Requires rack, rails, airflow planning
Blade server	High-density compute with shared chassis	Centralized power, cooling, networking	Chassis dependency, vendor ecosystem
Modular / composable	Flexible pools of compute, storage, network	Resource pooling and automation	Complexity, management tooling reliance
Edge server	Remote site, low-latency workloads	Local processing near users/devices	Physical security, limited hands-on support

Notes and examples

Core Components

Component	Exam-relevant details	Common trap
CPU	Sockets, cores, threads, cache, virtualization extensions, thermal design	More cores do not fix storage or network bottlenecks
Memory	ECC, registered/buffered DIMMs, speed compatibility, channel population rules	Mixing unsupported DIMM types can prevent boot or reduce performance
System board	Chipset, firmware, expansion slots, TPM, BMC/OOB management	Firmware settings can disable devices or virtualization features
PSU	Redundant supplies, hot-swap, power capacity, separate circuits	Redundant PSUs should not feed the same single point of power failure
Fans/cooling	Airflow direction, hot/cold aisles, sensors, thermal shutdown	Cable clutter and blanking-panel gaps can create hotspots
Expansion cards	NICs, HBAs, RAID controllers, GPUs, accelerators	PCIe slot lane/speed compatibility matters
BMC/OOB	IPMI, iLO, iDRAC-style functions, remote console, power control	OOB networks must be secured like administrative networks

Memory Concepts

Term	Meaning	Why it matters
ECC	Detects and corrects certain memory errors	Common server reliability requirement
Registered/buffered DIMM	Uses a register to reduce electrical load	Supports larger memory configurations
Unbuffered DIMM	Common in desktops/smaller systems	Often not supported in enterprise servers
Memory channel	Parallel path between CPU and DIMMs	Balanced channel population improves bandwidth
NUMA	Memory locality across CPU sockets	Poor VM or workload placement can reduce performance
Memory mirroring	Duplicates memory contents for fault tolerance	Reduces usable capacity
Memory sparing	Reserves memory to replace failing memory regions	Capacity tradeoff for resilience

Server platforms and form factors

Component/concept	Review point	Decision rule
Rack server	Standard data center form factor; measured in rack units	Good for scalable, centralized environments
Tower server	Standalone chassis	Good for small offices or low-density deployments
Blade server	High-density modular server in chassis	Watch shared chassis dependencies: power, cooling, networking
Hot-swappable component	Can be replaced without shutting down if supported	Confirm the component and platform support hot-swap
Redundant component	Duplicate component for availability	Redundancy reduces downtime but does not remove maintenance risk
Out-of-band management	Dedicated management path independent of OS	Useful when OS/network services are down

CPU, memory, and motherboard review

Topic	High-yield points
CPU sockets	Match CPU generation, socket, chipset, firmware, and supported memory type
Cores vs threads	More cores help parallel workloads; threads are logical execution paths
NUMA	Memory access may be faster when local to a CPU socket; relevant in multi-socket servers and virtualization
CPU virtualization support	Required or helpful for hardware-assisted virtualization features
ECC memory	Detects and corrects many memory errors; common in servers
RDIMM/LRDIMM/UDIMM	Do not mix unsupported memory types; follow vendor population rules
Memory channels	Balanced population improves performance
Firmware/BIOS/UEFI	Controls hardware initialization, boot order, security options, virtualization options
TPM	Hardware root of trust used for measured boot, encryption key protection, and platform integrity features

Power and cooling

Item	What to remember
Redundant PSU	Usually supports continued operation after one PSU failure if load capacity is adequate
UPS	Provides temporary power and graceful shutdown capability
PDU	Distributes power in rack environments; may be metered or managed
Cooling	Airflow direction, blanking panels, cable management, and ambient temperature matter
Environmental monitoring	Watch temperature, humidity, airflow, smoke, water, and power events

Hardware mistake patterns

Installing unsupported RAM because the speed or capacity “looks compatible.”
Forgetting to update firmware before troubleshooting known hardware compatibility issues.
Replacing a failed part without checking logs, indicators, firmware, or environmental causes.
Assuming redundant power works when both PSUs are plugged into the same failed power source.
Ignoring server vendor hardware compatibility lists for HBAs, NICs, drives, and firmware.

Storage Cheat Sheet

Storage Media and Interfaces

Technology	Choose when	Notes
HDD	Capacity-sensitive, sequential workloads, lower cost per capacity	Higher latency than SSD/NVMe
SATA SSD	General-purpose solid-state storage	Usually lower performance than SAS/NVMe enterprise options
SAS HDD/SSD	Enterprise server storage, dual-port paths, reliability features	Common with hardware RAID and backplanes
NVMe	Low-latency, high-IOPS workloads	Uses PCIe; excellent for databases and virtualization
M.2	Compact internal storage	Check thermal and enterprise durability requirements
U.2/U.3	Hot-swap-capable NVMe in server bays	More server-friendly than consumer M.2
Tape	Long-term retention, offline backup, archival	Slow restores; strong ransomware isolation when offline

Notes and examples

DAS, NAS, and SAN

Storage type	Description	Best for	Exam distinction
DAS	Direct-attached storage inside or cabled to one server	Local performance, simple deployments	Not inherently shared
NAS	File-level storage over network	SMB/NFS shares, user files, shared repositories	Clients access files
SAN	Block-level storage over dedicated or converged fabric	Databases, virtualization datastores, clustering	Servers see LUNs as disks
Object storage	Data stored as objects with metadata	Cloud-native apps, backups, large unstructured data	Accessed through APIs, not mounted like a local disk

RAID Selection Matrix

RAID level	Minimum disks	Usable capacity pattern	Fault tolerance	Performance profile	Use when
RAID 0	2	Sum of disks	None	High read/write	Temporary data only; never for resilience
RAID 1	2	Size of one disk per mirror	One disk per mirror set	Good read, normal write	OS volumes, simple redundancy
RAID 5	3	Total minus one disk	One disk	Good read, parity write penalty	Read-heavy workloads with moderate capacity efficiency
RAID 6	4	Total minus two disks	Two disks	Good read, larger parity write penalty	Larger arrays where rebuild risk matters
RAID 10	4	About half total	One disk per mirror pair	Strong read/write	Databases, virtualization, high performance plus resilience
Hot spare	Additional disk	Not active capacity	Speeds rebuild start	N/A	Reduce time exposed after disk failure

High-yield RAID traps

RAID is availability, not backup. It does not protect against deletion, corruption, ransomware, or site loss.
Rebuilds stress remaining disks and reduce performance.
Hardware RAID uses a controller; software RAID uses the OS or hypervisor.
Battery-backed or flash-backed write cache protects cached writes during power loss.
Replacing the wrong disk in a degraded array can cause data loss.

Storage Networking Terms

Term	Meaning	Key distinction
HBA	Host bus adapter for storage connectivity	Common with Fibre Channel or SAS
RAID controller	Manages RAID sets and cache	Presents logical volumes to OS
LUN	Logical unit presented by SAN	Server treats it like block storage
WWN / WWPN	Fibre Channel identifiers	Similar role to unique network identity
iSCSI	SCSI commands over TCP/IP	Uses standard IP networks; secure and isolate it
Fibre Channel	Dedicated storage fabric	High performance, specialized switches/HBAs
FCoE	Fibre Channel over Ethernet	Requires compatible converged infrastructure
Multipathing	Multiple paths to storage	Improves availability and can balance I/O
Thin provisioning	Allocates storage on demand	Risk of overcommit if not monitored
Thick provisioning	Allocates storage up front	Predictable capacity reservation
Snapshot	Point-in-time copy or reference	Useful for rollback; not a full backup by itself

Drive and interface basics

Technology	Typical use	Exam-relevant distinction
SATA	Cost-effective local storage	Lower enterprise feature set than SAS in many server contexts
SAS	Enterprise server storage	Dual-port capability, reliability features, common in arrays
NVMe	High-performance SSD over PCIe	Much lower latency than SATA/SAS SSDs
HDD	Capacity-focused storage	Mechanical latency; watch failure and rebuild times
SSD	Performance-focused storage	Endurance, write amplification, and firmware matter
HBA	Connects server to storage devices/arrays	May expose disks directly or connect to SAN
RAID controller	Manages RAID sets	Cache protection is important for write-back cache

RAID levels

RAID level	Minimum disks	Capacity concept	Fault tolerance	Best-fit idea	Trap
RAID 0	2	Sum of disks	None	Performance only	One disk failure loses array
RAID 1	2	Size of one disk per mirror	One disk per mirror set	Simple redundancy	Not capacity-efficient
RAID 5	3	Total minus one disk	One disk	Read-heavy, capacity-conscious	Risky during long rebuilds
RAID 6	4	Total minus two disks	Two disks	Better protection than RAID 5	More write penalty
RAID 10	4	Half of total	One disk per mirror pair	Performance plus redundancy	Needs more disks

Important distinction: RAID is availability technology, not backup technology. RAID may protect against a disk failure, but it does not protect against deletion, corruption, ransomware, failed updates, or site loss.

Storage architecture

Architecture	Meaning	High-yield notes
DAS	Direct-attached storage	Simple, local, limited sharing
NAS	File-level network storage	Common protocols include SMB and NFS
SAN	Block-level storage network	Common technologies include iSCSI and Fibre Channel
Object storage	Stores objects with metadata	Often used for scale-out and cloud-style storage
LUN	Logical unit presented from storage	Hosts see LUNs as block devices
Thin provisioning	Allocates physical storage as used	Monitor oversubscription carefully
Thick provisioning	Allocates storage upfront	Predictable allocation, less flexible
Multipathing	Multiple paths to storage	Provides path redundancy and sometimes load balancing
Zoning/masking	Controls SAN visibility/access	Do not expose all storage to all hosts

Storage troubleshooting clues

Symptom	Likely areas to check
Slow disk performance	Latency, queue depth, failed disk, rebuild, controller cache, path failure
Host cannot see LUN	Zoning, masking, initiator IQN/WWN, multipath, HBA driver, cabling
RAID degraded	Identify failed disk, check hot spare, verify rebuild status, replace supported disk
File share unavailable	Network path, DNS, permissions, service status, storage capacity
Unexpected low capacity	RAID overhead, formatting, snapshots, thin provisioning reserve, vendor capacity units

Server Networking Reference

Network Services and Protocols

Service/protocol	Common port(s)	Used for	Exam notes
SSH	TCP 22	Secure remote shell	Prefer keys/MFA where possible
Telnet	TCP 23	Legacy remote shell	Insecure; avoid except legacy troubleshooting
SMTP	TCP 25, 587, 465	Mail transfer/submission	587 commonly for authenticated submission
DNS	TCP/UDP 53	Name resolution	TCP often for zone transfers/large responses
DHCP	UDP 67/68	Automatic IP configuration	Relay/IP helper needed across subnets
HTTP	TCP 80	Web traffic	Redirect to HTTPS where appropriate
HTTPS	TCP 443	Encrypted web traffic	Certificate trust and hostname match matter
Kerberos	TCP/UDP 88	Ticket-based authentication	Time synchronization is critical
POP3	TCP 110/995	Mail retrieval	995 is encrypted POP3S
IMAP	TCP 143/993	Mail access/sync	993 is encrypted IMAPS
NTP	UDP 123	Time synchronization	Important for logs, Kerberos, certificates
LDAP	TCP/UDP 389	Directory queries	Use LDAPS or StartTLS for protection
LDAPS	TCP 636	LDAP over TLS	Certificate trust required
SMB/CIFS	TCP 445	Windows file/printer sharing	Common target for lateral movement
SNMP	UDP 161/162	Monitoring and traps	Prefer secure versions and restricted sources
RDP	TCP/UDP 3389	Windows remote desktop	Restrict, monitor, and protect with MFA/VPN
NFS	TCP/UDP 2049	Unix/Linux file sharing	Export permissions are critical
iSCSI	TCP 3260	Block storage over IP	Isolate and secure storage networks
Syslog	UDP/TCP 514, TLS 6514	Log forwarding	Centralize logs for correlation

Notes and examples

VLANs, Trunks, and Segmentation

Concept	Meaning	Use case
Access port	Carries one untagged VLAN	Server NIC for a single network
Trunk port	Carries multiple tagged VLANs	Hypervisor host, router, firewall, switch uplink
Native VLAN	Untagged VLAN on a trunk	Misconfiguration can cause security issues
Management VLAN	Admin interfaces and OOB access	Restrict access tightly
Storage VLAN	iSCSI/NFS/storage traffic	Reduce contention and exposure
DMZ	Semi-trusted network zone	Public-facing services isolated from internal systems
East-west traffic	Server-to-server traffic	Important for microsegmentation
North-south traffic	Client-to-server or internet-to-data-center traffic	Common firewall/load-balancer path

NIC Teaming and Link Aggregation

Method	Purpose	Key requirement
Active/passive failover	One NIC active, one standby	Switch support often simpler
Active/active load balancing	Multiple NICs carry traffic	Algorithm and switch compatibility matter
LACP / 802.3ad	Standards-based link aggregation	Switch ports must be configured as a group
Switch-independent teaming	Host controls failover/load distribution	Less switch configuration, fewer aggregation benefits
SR-IOV	VM direct access to NIC capabilities	Improves performance, may reduce mobility features

Common trap: NIC teaming improves availability and aggregate throughput, but one flow may not exceed the speed of a single physical link depending on hashing and configuration.

Load Balancing Patterns

Pattern	Description	Choose when
Layer 4 load balancing	Balances TCP/UDP connections	Fast transport-level distribution
Layer 7 load balancing	Uses HTTP headers, paths, cookies	Application-aware routing
Round robin	Rotates requests across targets	Simple distribution
Least connections	Sends to server with fewer active connections	Uneven session duration
Source IP persistence	Same client IP goes to same backend	Basic session stickiness
Cookie persistence	Application/session stickiness via cookie	Web apps needing session affinity
Active/passive	Standby node waits for failover	Simpler resilience
Active/active	Multiple nodes serve traffic	Better capacity utilization

Core network concepts

Concept	What to know
IP address	Logical address assigned to an interface
Subnet mask/prefix	Defines network vs host portion
Default gateway	Route used for off-subnet traffic
DNS	Name-to-address resolution; critical for authentication and services
DHCP	Dynamic address assignment; servers often use static or reserved addresses
NTP	Time synchronization; important for logs, certificates, authentication, and clustering
VLAN	Layer 2 segmentation
Trunk port	Carries multiple VLANs using tagging
Access port	Carries one VLAN, usually untagged
MTU	Maximum frame size; mismatch can cause fragmentation or connectivity problems
Jumbo frames	Larger MTU; must be supported end-to-end
NIC teaming/bonding	Redundancy and/or throughput depending on mode
LACP	Dynamic link aggregation; requires switch support/configuration

Common ports and protocols

Port	Protocol/service	Review note
22	SSH	Secure remote shell and administration
25	SMTP	Mail transfer
53	DNS	Name resolution
67/68	DHCP	Address assignment
80	HTTP	Unencrypted web traffic
88	Kerberos	Authentication in many enterprise environments
123	NTP	Time synchronization
135	Microsoft RPC	Windows service communication
139/445	SMB/CIFS	Windows file sharing
143	IMAP	Mail retrieval
161/162	SNMP	Monitoring and traps
389	LDAP	Directory queries
443	HTTPS	Encrypted web traffic
445	SMB	File/printer sharing and admin shares
514	Syslog	Centralized logging
636	LDAPS	LDAP over TLS
3389	RDP	Windows remote desktop
3260	iSCSI	Block storage over IP

Server networking decision rules

If name-based access fails but IP access works, check DNS first.
If off-subnet traffic fails, check default gateway, route table, firewall, and VLAN.
If one server cannot connect but others can, compare IP, subnet, gateway, DNS, VLAN, firewall, and host routes.
If performance is inconsistent, check duplex/speed negotiation, MTU mismatch, NIC drivers, switch errors, and congestion.
If storage over IP is unstable, check dedicated VLANs, jumbo frame consistency, multipathing, latency, and packet loss.
If time-sensitive authentication fails, check NTP and clock skew.

Virtualization, Containers, and Hybrid Infrastructure

Virtualization Decision Table

Concept	Meaning	Exam focus
Type 1 hypervisor	Runs directly on hardware	Enterprise server virtualization
Type 2 hypervisor	Runs on a host OS	Lab, desktop, testing
VM	Full virtual machine with virtual hardware	Strong isolation, OS flexibility
Container	Process-level isolation using shared kernel	Lightweight app deployment
vSwitch	Virtual switch inside hypervisor	Connects VMs to networks/VLANs
Datastore	Storage location for VM files/disks	Performance and redundancy matter
Template	Preconfigured VM image	Standardized deployment
Clone	Copy of a VM	Useful for testing or rapid provisioning
Snapshot	VM point-in-time state	Short-term rollback; not a backup
Live migration	Move running VM between hosts	Requires shared/compatible resources
HA cluster	Restarts workloads after host failure	Not the same as application-level clustering

Notes and examples

VM Resource Sizing Traps

Symptom	Possible cause	What to check
High CPU ready/wait	Overcommitted host CPU	vCPU allocation, host utilization
Guest reports low memory	VM underallocated or ballooning/swapping	Hypervisor memory metrics
Poor disk latency	Datastore contention	IOPS, latency, queue depth, noisy neighbors
Network drops	vSwitch/VLAN/NIC teaming issue	VLAN tags, MTU, uplinks, logs
Failed migration	CPU compatibility, network/storage mismatch	Cluster settings and host compatibility

Containers vs VMs

Use containers when	Use VMs when
App is stateless or cloud-native	Different OS kernels are needed
Fast scaling and deployment matter	Stronger isolation boundaries are required
Image-based deployment is mature	Legacy apps need full OS dependencies
Orchestration is available	Traditional administration model is preferred

Operating System Administration

Windows and Linux Administration Equivalents

Task	Windows examples	Linux examples
View IP configuration	`ipconfig`, `Get-NetIPConfiguration`	`ip addr`, `nmcli`
Test connectivity	`ping`, `tracert`, `Test-NetConnection`	`ping`, `traceroute`, `tracepath`
View listening ports	`netstat`, `Get-NetTCPConnection`	`ss -tulpen`, `netstat`
Manage services	Services console, `Get-Service`, `Restart-Service`	`systemctl status/start/stop`
View logs	Event Viewer, `Get-WinEvent`	`journalctl`, `/var/log/*`
Disk/volume info	Disk Management, `Get-Disk`, `Get-Volume`	`lsblk`, `df -h`, `du -sh`
Process monitoring	Task Manager, Resource Monitor	`top`, `htop`, `ps`, `pidstat`
Package updates	Windows Update, vendor tools	`apt`, `dnf`, `yum`, `zypper`
Permissions	NTFS ACLs, share permissions	POSIX mode bits, ACLs, ownership
Scheduled tasks	Task Scheduler	`cron`, `systemd timers`

Notes and examples

High-Value Commands

## Windows: service, network, and log checks
Get-Service | Where-Object Status -ne "Running"
Test-NetConnection server01 -Port 443
Get-NetIPConfiguration
Get-WinEvent -LogName System -MaxEvents 20
Get-Volume

## Linux: service, network, disk, and log checks
systemctl status nginx
ss -tulpen
ip route
df -h
lsblk
journalctl -u nginx --since "1 hour ago"

Item	Windows	Linux/Unix	Exam focus
Common file systems	NTFS, ReFS	ext4, XFS, Btrfs, ZFS	Features, compatibility, resilience
File sharing	SMB/CIFS	NFS, SMB	Authentication and permissions
Permissions	NTFS ACLs and share ACLs	Owner/group/other, ACLs	Effective access can be cumulative/restrictive
Mounting	Drive letters, mount points	`/etc/fstab`, `mount`	Persistent mounts need correct identifiers/options
Quotas	User/folder/volume quotas	Filesystem/user quotas	Prevent one user/app from consuming all capacity

Permission trap: For Windows file shares, effective access is constrained by both share permissions and NTFS permissions. The most restrictive combination often determines access.

Windows and Linux administration themes

Task	Windows examples	Linux examples	What SK0-006-style questions often test
Service management	Services console, PowerShell	systemctl, service	Start/stop/restart, startup behavior, dependency failures
Logs	Event Viewer, Windows logs	journalctl, /var/log	Finding evidence before changing settings
Users/groups	Local Users and Groups, AD tools	useradd, groupadd, passwd	Least privilege and group-based access
Permissions	NTFS permissions, share permissions	chmod, chown, ACLs	Effective access, inheritance, ownership
Package/patching	Windows Update, WSUS, vendor tools	apt, dnf/yum, zypper	Test, approve, deploy, rollback
Scheduling	Task Scheduler	cron, systemd timers	Automation and recurring maintenance
Scripting	PowerShell	Bash/Python	Repeatable administration and safe automation
Performance	Performance Monitor	top, ps, iostat, vmstat	CPU, memory, disk, and network baselines

Permissions review

Permission concept	High-yield note
Least privilege	Grant only what is needed for the role
Group-based access	Easier to manage than direct user permissions
Inheritance	Permissions may flow from parent folders/objects
Explicit deny	Often overrides allow rules; use carefully
Ownership	Owners may be able to change permissions depending on platform
Share vs file permissions	Effective access may be the most restrictive combination
Privilege escalation	Avoid giving admin/root rights for routine tasks

Patch and change management

Good SK0-006 answers usually prefer controlled change over ad hoc fixes:

Identify the risk or vulnerability.
Verify applicability and compatibility.
Test in a non-production or limited environment when feasible.
Schedule maintenance and notify stakeholders.
Back up or confirm rollback options.
Apply the update.
Validate services.
Document the change.

Useful command review

Need	Windows	Linux
IP configuration	ipconfig, Get-NetIPConfiguration	ip addr, nmcli
Connectivity test	ping, Test-NetConnection	ping, traceroute, tracepath
Route table	route print, Get-NetRoute	ip route
DNS lookup	nslookup, Resolve-DnsName	dig, nslookup, host
Listening ports	netstat, Get-NetTCPConnection	ss, netstat
Processes	Task Manager, Get-Process	ps, top, htop
Services	services.msc, Get-Service	systemctl
Logs	Event Viewer, Get-EventLog	journalctl, tail
Disk usage	Disk Management, Get-Volume	df, du, lsblk
Filesystem check	chkdsk	fsck
Permissions	icacls	chmod, chown, getfacl, setfacl

Identity, Access, and Secure Administration

Authentication and Authorization

Concept	Meaning	Use when
Authentication	Proves identity	Login, service account validation
Authorization	Grants permitted actions	File access, admin role, API permission
Accounting/auditing	Records activity	Compliance, investigations, nonrepudiation
Local account	Exists on one system	Break-glass or isolated systems
Directory account	Centralized identity	Enterprise access management
Service account	Runs an application/service	Use least privilege and rotate credentials
Privileged account	Admin-level permissions	Protect with MFA, logging, separation
RBAC	Permissions based on role	Scalable access management
ACL	Object-specific allow/deny entries	File, folder, network, or object control

Notes and examples

Common Identity Protocols

Protocol	Purpose	Important distinction
LDAP	Directory query/update	Not inherently encrypted unless protected
LDAPS / StartTLS	Encrypted LDAP	Requires certificate trust
Kerberos	Ticket-based authentication	Time skew causes failures
RADIUS	Centralized network authentication	Common for VPN, wireless, network devices
TACACS+	Device administration AAA	Separates authentication, authorization, accounting
SAML	Browser-based federation	Common for SSO to web apps
OAuth / OIDC	Delegated authorization / identity layer	Common for modern app authentication
SSH keys	Key-based remote administration	Protect private keys and disable weak access

Secure Administration Checklist

Use least privilege; avoid daily use of full administrator/root accounts.
Require MFA for privileged and remote access where supported.
Use named admin accounts instead of shared admin accounts.
Disable or rename default accounts where appropriate.
Restrict management interfaces to management networks or VPNs.
Use secure protocols: SSH, HTTPS, LDAPS, SNMPv3, TLS-protected syslog where supported.
Store secrets in approved secret-management tools, not scripts or plain-text files.
Log administrative actions centrally.
Review permissions and group membership regularly.
Use break-glass accounts carefully, monitor them, and protect credentials offline.

Security Controls and Hardening

Control Types

Control type	Examples	Purpose
Administrative	Policies, procedures, training, change control	Direct human and process behavior
Technical	Firewalls, ACLs, encryption, MFA, EDR	Enforce security through systems
Physical	Locks, cameras, badges, cages, guards	Protect facilities and equipment
Preventive	Hardening, access control, patching	Stop incidents before they occur
Detective	Logs, IDS, alerts, file integrity monitoring	Identify suspicious activity
Corrective	Restore from backup, reimage, patch	Recover after an issue
Compensating	Alternate control when primary is not feasible	Reduce risk when ideal control cannot be used

Notes and examples

Server Hardening Matrix

Area	Hardening action	Why it matters
Firmware	Update firmware, protect setup access, enable Secure Boot where appropriate	Reduces low-level attack surface
OS	Remove unused roles/features, patch regularly	Fewer exploitable services
Accounts	Disable unused accounts, enforce strong authentication	Reduces credential risk
Services	Stop and disable unnecessary services	Reduces listening ports
Network	Host firewall, segmentation, restrict admin ports	Limits lateral movement
Files	Least-privilege ACLs, integrity monitoring	Protects sensitive data
Logs	Centralize and protect logs	Attackers often tamper with local logs
Encryption	TLS in transit, encryption at rest	Protects data exposure
Anti-malware/EDR	Deploy, update, monitor	Detects known and suspicious activity
Configuration	Baselines, drift detection	Finds unauthorized changes

Certificate and TLS Pitfalls

Symptom	Likely cause	Check
Browser warning	Expired, untrusted, or mismatched certificate	CN/SAN, chain, expiration, trust store
TLS handshake failure	Protocol/cipher mismatch	Supported TLS versions and cipher suites
LDAPS failure	Directory server certificate issue	Certificate chain and hostname
Mutual TLS failure	Client cert missing/untrusted	Client certificate mapping and CA trust
Intermittent cert errors	Load-balanced nodes differ	Cert installed consistently on all nodes

Security principles

Principle	Server+ relevance
Confidentiality	Protect data from unauthorized disclosure
Integrity	Prevent or detect unauthorized modification
Availability	Keep systems and services operational
Least privilege	Minimize permissions and admin access
Defense in depth	Layer physical, network, host, app, and data controls
Secure by default	Disable unnecessary services and default accounts
Accountability	Use logging, auditing, and named accounts

Hardening checklist

Area	High-yield actions
Accounts	Disable unused/default accounts, enforce strong authentication, use MFA where appropriate
Privileges	Use RBAC, separate admin accounts, avoid shared admin credentials
Services	Disable unnecessary services, close unused ports
Network	Host firewall, segmentation, secure management networks
Remote access	Prefer encrypted protocols such as SSH/HTTPS; restrict RDP/management access
Patching	Apply OS, firmware, hypervisor, driver, and application updates through change control
Encryption	Protect data at rest and in transit where required
Boot integrity	Use UEFI security features, secure boot, TPM-backed protections where applicable
Logging	Centralize logs, protect logs from tampering, monitor alerts
Physical security	Locks, badges, cameras, cages, console access control
Baselines	Compare current state to approved secure configuration

Authentication and directory concepts

Concept	What to remember
Authentication	Proves identity
Authorization	Determines allowed actions
Accounting/auditing	Records activity
LDAP/LDAPS	Directory access; LDAPS adds encryption
Kerberos	Ticket-based authentication; time synchronization matters
MFA	Combines factors to reduce credential-only risk
SSO	One authentication event grants access to multiple services
Federation	Trust relationship across identity providers/domains
Service account	Account used by services; should have limited, documented privileges

Certificate and encryption traps

An encrypted protocol does not help if the certificate is expired, untrusted, mismatched, or using the wrong name.
Self-signed certificates may be acceptable in labs but usually create trust and management issues.
Private keys must be protected; losing a key can break decryption or service identity.
Encryption at rest does not replace access control.
TLS protects traffic in transit, not necessarily data once stored or processed.

Backup, Resilience, and Disaster Recovery

Key Metrics

Metric	Meaning	Exam use
RTO	Recovery Time Objective: maximum acceptable time to restore service	Determines recovery architecture
RPO	Recovery Point Objective: maximum acceptable data loss measured in time	Determines backup/replication frequency
MTTR	Mean Time To Repair/Recover	Measures restoration speed
MTBF	Mean Time Between Failures	Reliability indicator
SLA	Service Level Agreement	Defines expected service commitments
MTTD	Mean Time To Detect	Detection speed for failures/incidents

Notes and examples

\[ \text{Availability} = \frac{\text{Uptime}}{\text{Total time}} \times 100 \]

Backup Types

Backup type	What it copies	Restore characteristics	Use when
Full	All selected data	Simplest restore	Baseline or smaller data sets
Incremental	Changes since last backup of any type	Restore needs last full plus incrementals	Save backup time/storage
Differential	Changes since last full	Restore needs last full plus latest differential	Faster restore than long incremental chains
Snapshot	Point-in-time state/reference	Fast rollback, storage-dependent	Short-term recovery before changes
Image/bare-metal	Entire system state	Full server recovery	OS/app rebuild time must be minimized
File-level	Selected files/folders	Granular recovery	User or application file restore
Application-aware	Coordinates with app/database	Consistent app recovery	Databases, email, transactional apps
Offline/air-gapped	Not continuously reachable	Strong ransomware resilience	Critical backups and long-term retention

Resilience vs Backup vs DR

Technology	Primary purpose	Does it replace backups?	Notes
RAID	Disk fault tolerance	No	Does not protect from deletion/corruption
Clustering	Service availability	No	Protects against node failure
Load balancing	Distribute traffic and improve availability	No	App state must be handled
Replication	Copy data to another location/system	No	Can replicate corruption or ransomware
Snapshots	Fast point-in-time rollback	No	Often depends on same storage platform
Backup	Recover data/system to a prior state	N/A	Must be tested
Disaster recovery site	Continue operations after major outage	No	Still needs data protection strategy

DR Site Models

Model	Description	Tradeoff
Cold site	Facility/infrastructure available, little or no live equipment	Lower cost, longer recovery
Warm site	Some preconfigured systems/data	Balanced cost and recovery time
Hot site	Ready-to-run duplicate environment	Faster recovery, higher cost/complexity
Cloud recovery	Restore or fail over to cloud resources	Requires network, identity, and data planning

Backup Validation Checklist

Confirm backups complete successfully; do not rely only on scheduled job existence.
Perform test restores, including full-system and application-level restores.
Validate backup encryption keys and recovery credentials.
Keep at least one copy protected from routine network access.
Monitor capacity for backup repositories and snapshot stores.
Document restore order for dependent systems.
Align backup frequency with RPO and recovery procedure with RTO.

Key recovery terms

Term	Meaning	Decision point
RTO	Recovery Time Objective: how quickly service must be restored	Drives architecture and recovery method
RPO	Recovery Point Objective: acceptable data loss window	Drives backup/replication frequency
MTTR	Mean Time To Repair/Recover	Useful for operational expectations
MTBF	Mean Time Between Failures	Reliability planning metric
HA	High availability	Reduces downtime, may not protect data from corruption
DR	Disaster recovery	Restores service after major failure
Failover	Move service to standby/alternate system	Must be tested
Failback	Return service to original/primary site	Can be risky without planning

Backup types

Backup type	What it does	Restore implication
Full	Backs up all selected data	Simplest restore, more time/storage
Incremental	Backs up changes since last backup of any type	Faster backup, may require multiple restore sets
Differential	Backs up changes since last full backup	Restore needs full plus latest differential
Image-based	Captures system/volume image	Useful for bare-metal or VM recovery
File-level	Captures selected files/folders	Good for granular restore
Application-aware	Coordinates with application state	Important for databases and transactional systems
Synthetic full	Builds full backup from prior backup data	Reduces production load depending on platform

Recovery design rules

RTO short? Consider clustering, replication, standby systems, automation, and documented runbooks.
RPO short? Increase backup frequency or use replication/journaling.
Ransomware concern? Use offline, immutable, or access-isolated backups.
Site failure concern? Keep copies off-site or in another region/location.
Critical restore? Test it. A backup is only proven when it can be restored.
Regulated or sensitive data? Protect backup confidentiality and access just like production data.

3-2-1 backup idea

A common review heuristic is:

3 copies of important data
2 different media or storage types
1 copy off-site or otherwise isolated

Use this as a concept, not as a substitute for analyzing RTO, RPO, retention, security, and restore testing.

Monitoring, Logging, and Performance

What to Monitor

Area	Metrics/signals	Common issue indicated
CPU	Utilization, load, run queue, CPU ready	Compute saturation or overcommit
Memory	Free/available memory, paging/swapping, ballooning	Memory pressure
Disk	Latency, IOPS, throughput, queue depth, SMART alerts	Storage bottleneck or failing media
Network	Throughput, errors, drops, retransmits, latency	Duplex, cabling, congestion, routing
Services	Process health, response time, restart events	App or dependency failure
Logs	Errors, warnings, authentication events, kernel/system events	Root-cause evidence
Hardware	Temperature, fan speed, PSU status, chassis intrusion	Environmental or physical failure
Backup	Job result, duration, repository capacity	Recovery risk
Security	Failed logins, privilege changes, malware alerts	Compromise or misuse

Notes and examples

Log Sources

Source	Use
OS system logs	Kernel, driver, service, boot issues
Application logs	App-specific errors and transactions
Security/auth logs	Login, privilege, policy, access events
Hypervisor logs	VM, host, datastore, migration problems
Storage logs	Disk, controller, path, array, replication events
Network device logs	Link, VLAN, routing, ACL, spanning tree issues
BMC/OOB logs	Hardware faults, thermal, power events
SIEM/log platform	Correlation across systems

Bottleneck Clues

Symptom	Likely bottleneck	Confirm with
High CPU, normal disk/network	CPU-bound workload	CPU graphs, process list
Low CPU, high disk latency	Storage bottleneck	Disk latency/queue, array stats
Heavy paging/swapping	Memory pressure	Memory counters, swap/pagefile usage
Slow file transfers, errors	Network/cabling/duplex/VLAN issue	Interface counters, switch logs
App slow only during backup	Backup contention	Backup schedule, disk/network metrics
VM slow but host busy	Resource contention	Hypervisor metrics
Users cannot authenticate	Directory/DNS/time issue	DNS lookup, NTP, directory logs
Intermittent failures after change	Misconfiguration or compatibility	Change records and rollback test

What to monitor

Resource	Useful indicators	Common interpretation
CPU	Utilization, run queue, ready time	Sustained high use may indicate load or inefficient processes
Memory	Free/available memory, paging/swapping	Heavy paging usually hurts performance
Disk	Latency, IOPS, throughput, queue depth	Latency is often more important than raw utilization
Network	Throughput, errors, drops, retransmits	Errors/drops suggest physical, driver, duplex, or congestion issues
Services	Up/down state, response time	Service availability is what users notice
Logs	Errors, warnings, audit events	Correlate timestamps across systems
Hardware	Temperature, fans, PSU, disk SMART/health	Hardware alerts often precede outages
Capacity	Growth trends	Prevent storage, CPU, and memory exhaustion

Baseline principle

A performance number is most useful when compared to a known-good baseline. “CPU is 70%” may be normal for one server and abnormal for another. Good troubleshooting compares:

Current behavior vs baseline
Affected server vs similar server
Before change vs after change
Peak vs non-peak periods
Application symptoms vs infrastructure metrics

Change, Patch, and Configuration Management

Change Management Flow

    flowchart TD
	    A[Identify need or issue] --> B[Assess risk and impact]
	    B --> C[Plan implementation]
	    C --> D[Plan rollback]
	    D --> E[Get approval if required]
	    E --> F[Communicate maintenance window]
	    F --> G[Implement change]
	    G --> H[Test and validate]
	    H --> I{Successful?}
	    I -- Yes --> J[Document final state]
	    I -- No --> K[Rollback or remediate]
	    K --> H

Notes and examples

Patch and Firmware Review

Task	Exam-relevant practice
Inventory	Know OS, firmware, drivers, apps, agents, dependencies
Test	Validate patches in nonproduction where possible
Schedule	Use maintenance windows for disruptive changes
Backup	Confirm recoverability before major updates
Dependencies	Check firmware-driver-OS compatibility
Order	Follow vendor guidance for firmware, drivers, hypervisor, and tools
Rollback	Have uninstall, snapshot, image, or failover plan
Verify	Confirm services, logs, performance, and user access
Document	Record versions, results, issues, and approvals

Documentation Artifacts

Artifact	Contains
Network diagram	VLANs, IP ranges, firewalls, load balancers, uplinks
Rack diagram	RU position, power feeds, cabling paths
Asset inventory	Serial numbers, warranty/support, owner, location
Baseline	Normal performance/configuration state
Runbook	Repeatable operational procedure
SOP	Standard procedure for common tasks
DR plan	Recovery sequence, contacts, dependencies
Change record	What changed, when, why, who approved, rollback
Credential escrow/break-glass process	Controlled emergency access

Troubleshooting Methodology

Standard Troubleshooting Pattern

Identify the problem.
- Gather symptoms, scope, timeline, error messages, and affected users.
- Determine what changed.
Establish a theory of probable cause.
- Start with simple, likely causes.
- Consider hardware, software, network, security, and environmental factors.
Test the theory.
- Confirm or reject with evidence.
- If rejected, form a new theory.
Establish a plan of action.
- Consider impact, risk, backups, and rollback.
Implement the solution or escalate.
Verify full system functionality.
- Confirm service health, logs, monitoring, and user impact.
Document findings, actions, and outcomes.

Fast Triage Table

Problem type	First checks	Useful tools
Server will not power on	Power source, PSU LEDs, PDU/UPS, power cables, BMC logs	OOB console, multimeter if appropriate, vendor diagnostics
POST/boot failure	Beep/LED codes, firmware settings, boot order, recent hardware change	BIOS/UEFI, hardware diagnostics
OS boot failure	Bootloader, disk visibility, recent patch/driver, filesystem errors	Recovery media, logs, safe mode/rescue mode
Disk failure	RAID status, SMART, controller logs, hot spare status	RAID utility, `smartctl`, vendor tools
Network unreachable	Link light, VLAN, IP, gateway, DNS, firewall	`ping`, `traceroute`, `ipconfig`, `ip`, switch logs
Slow performance	CPU, memory, disk latency, network errors, recent jobs	Performance monitor, `top`, `iostat`, hypervisor metrics
Service down	Process state, dependencies, port binding, config changes	`systemctl`, Services, logs, `ss`, `netstat`
Authentication failure	Time sync, DNS, account lockout, directory reachability	NTP checks, directory logs, `nslookup`
Backup failure	Credentials, repository space, network path, agent status	Backup console, logs, storage metrics
Overheating	Fans, airflow, blocked vents, room temperature, dust	BMC sensors, environmental monitoring

Notes and examples

Practical SK0-006 troubleshooting flow

    flowchart TD
	    A[Identify the problem] --> B[Gather information and symptoms]
	    B --> C[Check recent changes, logs, alerts, and scope]
	    C --> D[Establish a theory]
	    D --> E[Test the theory safely]
	    E --> F{Theory confirmed?}
	    F -- No --> G[Revise theory or escalate with evidence]
	    G --> D
	    F -- Yes --> H[Plan the fix and rollback]
	    H --> I[Implement one controlled change]
	    I --> J[Verify full system functionality]
	    J --> K[Document cause, fix, and prevention]

Fast isolation questions

Question	Why it matters
Who is affected?	One user, one app, one server, one VLAN, or everyone?
What changed?	Patches, firmware, firewall, certificates, DNS, storage, credentials
When did it start?	Correlate with logs, monitoring, backups, jobs, and maintenance
Is it reproducible?	Intermittent issues need monitoring and pattern analysis
Is there a workaround?	Reduces business impact while root cause is investigated
What is the rollback?	Prevents a fix from becoming a larger outage

Symptom-to-cause review

Symptom	First checks	Deeper checks
Server will not boot	Power, LEDs, console, boot order, recent hardware	RAID status, firmware, OS bootloader, failed disk
Random shutdowns	Power, UPS, thermal alerts	PSU load, fans, airflow, motherboard, firmware
Slow application	CPU/memory/disk/network, service health	Database locks, storage latency, DNS, authentication
Cannot authenticate	Account status, password, time sync	Directory service health, DNS, Kerberos/LDAP, certificates
Cannot access file share	Network, DNS, share path	Share permissions, NTFS/Linux permissions, service status
VM will not start	Host resources, datastore space	Snapshots, locks, hypervisor tools, compatibility
Backup failed	Credentials, target space, network	VSS/app consistency, repository health, permissions
Storage path down	Cable/link, switch, HBA/NIC	Zoning, masking, multipath, firmware/driver

Scenario Decision Tables

“What Should You Do First?”

Scenario	Best first action
Many users report a new outage after a maintenance window	Review change records and recent changes
One server loses network connectivity after recabling	Check physical link, switch port, VLAN, and cable
Disk alert on a RAID array	Verify array status and identify the failed disk before replacement
Authentication failures across multiple servers	Check directory services, DNS, and time synchronization
One VM is slow while others are normal	Check VM-level resource usage and host contention
All VMs on one host are impacted	Check host hardware, storage paths, and hypervisor logs
Web app works by IP but not name	Check DNS records and resolution path
HTTPS site shows trust warning	Check certificate validity, hostname, chain, and trust store
Backup jobs suddenly fail	Check repository capacity, credentials, network access, and agent health
Server shuts down under load	Check thermal sensors, fans, CPU heatsinks, and power capacity

Notes and examples

“Which Technology Solves This?”

Requirement	Best fit
Survive one disk failure	RAID 1/5/6/10 depending on workload and capacity
Restore deleted files from last week	Backup
Quickly roll back a pre-patch VM state	Snapshot, with backup still required
Keep service running if one node fails	Cluster or load-balanced redundant nodes
Spread web requests across servers	Load balancer
Copy data to another site for DR	Replication plus tested recovery plan
Authenticate switch/VPN users centrally	RADIUS or TACACS+ depending on use case
Secure remote shell access	SSH with strong authentication
Secure web administration	HTTPS with trusted certificate
Isolate public-facing servers	DMZ and firewall rules
Monitor hardware health without OS access	BMC/OOB management
Provide shared file storage	NAS with SMB/NFS
Provide block storage to hosts	SAN/iSCSI/Fibre Channel
Improve admin consistency	Automation, templates, configuration management

Physical, Power, and Environmental Reference

Data Center and Server Room Essentials

Area	Key points
Rack layout	Balance weight, mount heavy equipment low, use proper rails
Airflow	Front-to-back airflow, hot/cold aisle discipline, blanking panels
Power	Redundant PSUs, PDUs, separate circuits where possible
UPS	Provides short-term power and graceful shutdown time
Generator	Longer-term facility power support
ESD	Use grounding/ESD precautions when handling components
Cable management	Label both ends, avoid blocking airflow, separate power/data when appropriate
Physical security	Locks, badges, cameras, visitor logs, cages
Fire suppression	Protect equipment and personnel; know local procedures
Environmental monitoring	Temperature, humidity, water, smoke, door status

Notes and examples

Power Concepts

Term	Meaning
Redundant PSU	Multiple power supplies in one server
PDU	Distributes power within a rack
Metered PDU	Provides power usage visibility
Switched PDU	Allows remote outlet control
UPS	Battery-backed power and conditioning
Graceful shutdown	Controlled OS/app shutdown to prevent corruption
Power budget	Ensures rack/circuit capacity supports connected load

High-Yield Exam Traps

Trap	Correct understanding
RAID equals backup	RAID improves disk availability; backup enables point-in-time recovery
Snapshot equals backup	Snapshots are short-term rollback aids and may depend on the same platform
More CPU fixes slowness	Determine bottleneck first: CPU, memory, disk, network, app, or dependency
Open firewall broadly to fix access	Test narrowly; apply least privilege rules
Ignore DNS when troubleshooting authentication	Directory services often depend heavily on DNS
Ignore time sync	Kerberos, logs, certificates, and distributed systems require accurate time
Replace hardware without checking logs	Logs and indicators prevent wrong-part replacement
Use shared admin accounts	Use named privileged accounts with auditing
Patch production without rollback	Always plan backup, rollback, and validation
Trust local logs after compromise	Centralized logs are more reliable for investigations
Put management interfaces on user networks	Isolate OOB and admin access
Assume replication protects against ransomware	Replication may copy encrypted/corrupted data
Overcommit VMs without monitoring	Oversubscription requires capacity monitoring and baselines
Leave default SNMP/community strings	Use secure versions and restrict access

Final Review Checklist

Before exam day, make sure you can:

Select server hardware based on workload, redundancy, expansion, and environment.
Compare RAID levels and explain failure/rebuild implications.
Distinguish DAS, NAS, SAN, iSCSI, Fibre Channel, and object storage.
Identify common ports and match protocols to server functions.
Troubleshoot DNS, DHCP, VLAN, routing, firewall, and load-balancer issues.
Administer basic Windows and Linux services, logs, storage, and networking.
Explain virtualization concepts: hypervisors, vSwitches, templates, snapshots, migration, HA.
Apply least privilege, secure administration, encryption, certificates, and hardening.
Compare backup types and map RTO/RPO to recovery designs.
Use a structured troubleshooting process and document outcomes.
Recognize environmental, power, cooling, and physical security issues.
Choose the best first step in scenario-based troubleshooting questions.

High-yield SK0-006 review map

Area	What to know cold	Common exam trap
Server hardware	CPUs, memory, firmware, power, cooling, expansion, out-of-band management	Treating desktop hardware assumptions as server-grade requirements
Storage	RAID, DAS/NAS/SAN, iSCSI, FC, LUNs, multipathing, hot spares, backups	Confusing redundancy with backup
Networking	VLANs, DNS, DHCP, NTP, routing basics, NIC teaming, ports, secure protocols	Troubleshooting IP before checking link/VLAN/DNS basics
Server OS administration	Services, logs, users/groups, permissions, patching, automation, monitoring	Ignoring least privilege or change control
Virtualization/cloud	Hypervisors, resource allocation, snapshots, templates, migration, containers	Treating snapshots as long-term backups
Security	Hardening, IAM, encryption, certificates, secure boot, patching, logging	Opening broad access to “make it work”
Disaster recovery	RTO, RPO, backup types, replication, failover, restore testing	Having backups that have never been restored
Troubleshooting	Methodical isolation, logs, baselines, rollback, documentation	Changing multiple variables at once

Virtualization, containers, and cloud

Virtualization concepts

Concept	Review point
Type 1 hypervisor	Runs directly on hardware; common for production virtualization
Type 2 hypervisor	Runs on top of a host OS; common for labs/dev
VM	Virtual machine with virtual CPU, memory, disk, and NICs
vCPU	Virtual CPU presented to VM; oversubscription must be managed
Memory ballooning	Hypervisor technique to reclaim memory
Datastore	Storage location for VM files/disks
Virtual switch	Software switch connecting VMs and physical networks
Template	Reusable VM baseline for consistent deployment
Snapshot	Point-in-time VM state; short-term rollback aid
Live migration	Move running VM between hosts when requirements are met
HA cluster	Restarts or moves workloads after host failure depending on platform design

Notes and examples

Snapshot vs backup

Feature	Snapshot	Backup
Main purpose	Short-term rollback	Recovery from loss/corruption
Storage dependency	Usually depends on source datastore	Should be recoverable independently
Duration	Short-lived	Retained according to policy
Risk	Performance growth/chain issues if left too long	Must be tested and protected
Exam rule	Not a replacement for backup	Required for real recovery planning

Cloud and container review

Concept	Meaning	Trap
IaaS	Provider offers compute/storage/network infrastructure	Customer still manages OS and many security controls
PaaS	Provider offers platform/runtime	Less OS control, more managed convenience
SaaS	Provider offers full application	Configuration and identity still matter
Private cloud	Cloud-like model for one organization	Still needs automation, pooling, monitoring
Hybrid cloud	Mix of private and public resources	Networking, identity, and data movement are critical
Container	Lightweight isolated application environment	Shares host kernel; not the same as a full VM
Orchestration	Automates deployment/scaling/health	Misconfiguration can expose services or secrets

Virtualization sizing traps

Giving every VM too many vCPUs can reduce performance through scheduling contention.
Thin-provisioned disks can cause outages if physical storage fills.
Snapshots left in place can consume datastore space and hurt performance.
VM backups must be application-consistent when required.
Live migration depends on compatible hosts, networking, shared/accessible storage, and resource capacity.
Time sync conflicts can occur if both guest tools and domain/NTP settings fight each other.

Common candidate mistakes

Memorizing ports without knowing when the service is used.
Confusing authentication with authorization.
Choosing RAID when the question asks for backup or disaster recovery.
Choosing a snapshot when the question asks for long-term recovery.
Ignoring DNS and NTP in authentication and certificate problems.
Overlooking firmware, drivers, and compatibility in hardware issues.
Applying a fix before gathering logs or confirming scope.
Recommending broad administrative permissions instead of least privilege.
Forgetting that high availability does not protect against data corruption.
Treating cloud services as if the provider manages every security responsibility.
Changing multiple settings at once and losing the ability to identify root cause.
Skipping documentation after resolving an incident.

High-yield decision rules

If the question asks for…	Prefer thinking about…
Disk failure with service continuity	RAID, hot spare, redundant paths, monitoring
Accidental deletion recovery	Backup, snapshot only if appropriate and recent
Site outage recovery	DR site, replication, off-site backups, runbooks
Minimal downtime	HA, clustering, live migration, redundancy
Minimal data loss	RPO, replication frequency, transaction-aware backups
Secure remote administration	SSH, HTTPS, VPN, MFA, restricted management network
Permission cleanup	Groups/RBAC, least privilege, inheritance review
Intermittent network issue	Cabling, errors, duplex/speed, MTU, switch logs
Name resolution failure	DNS records, resolver settings, suffixes, caching
Authentication failure	Time sync, directory service, account state, DNS
Performance investigation	Baseline, bottleneck metrics, one change at a time
Compliance-style evidence	Logs, audit trails, access reviews, documentation

Topic drills to pair with this Cheat Sheet

Use this page as a checklist, then move into IT Mastery practice. Strong SK0-006 preparation should include original practice questions in these drill sets:

Drill set	What to practice
RAID and storage	Select RAID levels, identify SAN/NAS issues, distinguish backup vs redundancy
Networking	Ports, VLANs, DNS, DHCP, NTP, NIC teaming, troubleshooting paths
Hardware	Memory compatibility, power/cooling, firmware, out-of-band management
OS administration	Services, logs, permissions, patching, scripting, command interpretation
Virtualization	Snapshots, resource allocation, migration, hypervisor networking/storage
Security	Hardening, IAM, certificates, encryption, secure remote access
Disaster recovery	RTO/RPO, backup types, replication, restore testing
Troubleshooting	Scenario-based root cause, safest next step, verification and documentation

Final quick pass before mock exams

Before starting a mixed question bank or mock exam, make sure you can answer these without looking:

Why is RAID not a backup?
When would RAID 10 be preferred over RAID 5 or RAID 6?
What is the difference between NAS and SAN?
What breaks when DNS is wrong on a server?
Why does NTP matter for authentication and certificates?
What is the difference between a snapshot and a backup?
What do RTO and RPO each measure?
What is the safest way to apply patches in production?
How do share permissions and file permissions combine?
What evidence should you collect before making a troubleshooting change?
Which logs or tools would you check first for a failed service?
How would you isolate whether a problem is host, network, storage, or application related?

Put the review into practice

Study Plan

SK0-006 — CompTIA Server+ V6 Cheat Sheet

Server Hardware Reference

Server Form Factors and Use Cases

Core Components

Memory Concepts

Server platforms and form factors

CPU, memory, and motherboard review

Power and cooling

Hardware mistake patterns

Storage Cheat Sheet

Storage Media and Interfaces

DAS, NAS, and SAN

RAID Selection Matrix

Storage Networking Terms

Drive and interface basics

RAID levels

Storage architecture

Storage troubleshooting clues

Server Networking Reference

Network Services and Protocols

VLANs, Trunks, and Segmentation

NIC Teaming and Link Aggregation

Load Balancing Patterns

Core network concepts

Common ports and protocols

Server networking decision rules

Virtualization, Containers, and Hybrid Infrastructure

Virtualization Decision Table

VM Resource Sizing Traps

Containers vs VMs

Operating System Administration

Windows and Linux Administration Equivalents

High-Value Commands

File Systems and Sharing

Windows and Linux administration themes

Permissions review

Patch and change management

Useful command review

Identity, Access, and Secure Administration

Authentication and Authorization

Common Identity Protocols

Secure Administration Checklist

Security Controls and Hardening

Control Types

Server Hardening Matrix

Certificate and TLS Pitfalls

Security principles

Hardening checklist

Authentication and directory concepts

Certificate and encryption traps

Backup, Resilience, and Disaster Recovery

Key Metrics

Backup Types

Resilience vs Backup vs DR

DR Site Models

Backup Validation Checklist

Key recovery terms

Backup types

Recovery design rules

3-2-1 backup idea

Monitoring, Logging, and Performance

What to Monitor

Log Sources

Bottleneck Clues

What to monitor

Baseline principle

Change, Patch, and Configuration Management

Change Management Flow

Patch and Firmware Review

Documentation Artifacts

Troubleshooting Methodology

Standard Troubleshooting Pattern

Fast Triage Table

Practical SK0-006 troubleshooting flow

Fast isolation questions

Symptom-to-cause review

Scenario Decision Tables

“What Should You Do First?”

“Which Technology Solves This?”

Physical, Power, and Environmental Reference