IT & SYSTEMS CHEAT-SHEET - GUIDINEE.COM
Quick reference to keep at hand during the capstone project.
NB: technology moves fast (versions, tools, cloud offers) -> always check the current official docs.

=== THE MINDSET ===
- IT RUNS, SECURES and EVOLVES the information system the business depends on.
- Build a broad GENERALIST base first (hardware, OS, network, accounts, cloud, security) before specializing.
- The real skill is not knowing EVERYTHING: it is knowing how to FIND, understand and keep learning.
- Security is never "finished": it is a continuous PROCESS (watch, improve, stay vigilant).
- The weakest link is often the HUMAN -> user awareness is one of the best investments.

=== HARDWARE & OS ===
- Workstation = serves 1 user | Server = serves MANY, continuously, reliably (redundancy, 24/7).
- OS = the layer between hardware and software; manages memory, files, devices.
  Windows (business desktops) | macOS (creative) | Linux (dominates on SERVERS, free, robust).
- Units: bit = smallest unit | byte = 8 bits | KB/MB/GB/TB (storage) != bits/s (BANDWIDTH).
- Installing Windows: BACK UP first -> install -> drivers -> updates -> accounts -> software -> restore data.

=== TROUBLESHOOTING (method) ===
1) Reproduce / understand the symptom   2) Identify what CHANGED
3) Go from SIMPLE to complex, ONE change at a time   4) Isolate the cause before acting
5) Record the solution (knowledge base) -> never re-solve the same issue twice.
- Driver = lets hardware talk to the OS | Licence = the RIGHT to use software (track it, do not neglect it).

=== USER SUPPORT (Tier 1) ===
- TICKETING: log, prioritize, track -> reveals RECURRING incidents (a deeper "problem").
- COMMUNICATION is a technical skill: listen, explain plainly (no jargon), reassure.
- Incident = restore service FAST | Problem = remove the CAUSE of recurring incidents.

=== NETWORK ===
- IP address = a machine's identifier | MASK = delimits the local network | GATEWAY = exit to other networks.
- DNS = phone book (name -> IP) | DHCP = automatically assigns IPs.
- SWITCH = connects devices WITHIN the LAN | ROUTER = connects networks (often inside the box).
- Diagnose nearest-to-farthest -> ipconfig (my config) | ping (reachable?) | tracert (the path).
- Shares (folders, printers): access by NEED (least privilege), manage permissions.

=== WINDOWS ADMIN & ACCOUNTS ===
- LEAST PRIVILEGE: grant only what is needed. Users on STANDARD accounts, not admin.
- Active Directory (domain) = CENTRAL management of accounts, computers and rights.
- GPO (Group Policy) = apply configs and security rules at scale, consistently.
- PowerShell = AUTOMATE the repetitive, act at scale reproducibly. Caution: TEST before running broadly.

=== BACKUP & RECOVERY ===
- 3-2-1 rule: 3 copies, 2 different media, 1 OFF-SITE. + at least one DISCONNECTED copy (anti-ransomware).
- A backup NEVER TESTED is worthless -> test restores regularly.
- DR = restart IT after a disaster | Business continuity = keep essentials running DURING the incident.
- RPO = data you accept LOSING (-> backup frequency) | RTO = acceptable RECOVERY time (-> resources).
  Set RPO/RTO by the CRITICALITY of each activity.

=== CLOUD & MICROSOFT 365 ===
- Cloud = consume computing as a SERVICE. SaaS (ready software) > PaaS (platform) > IaaS (infrastructure).
  The higher toward SaaS: the less you manage, but the less you control.
- M365 admin: accounts, LICENCES, groups -> managed from the cloud console (not machine by machine).
- OneDrive (personal) | SharePoint (team) | Teams (collaboration) -> manage rights and sharing CAREFULLY.
- MFA (via Entra ID): blocks most account attacks -> ENFORCE it. A stolen password is no longer enough.
- Virtualization = several VIRTUAL machines on one host (consolidate, test, build a LAB safely).

=== CYBERSECURITY FROM THE IT SIDE (defense in depth) ===
Reduce the ATTACK surface + stack layers (none is infallible):
UPDATES (close known holes) | FIREWALL | up-to-date ANTIVIRUS | HARDENING (disable the unnecessary)
LEAST PRIVILEGE | MFA | disk ENCRYPTION (mobile devices) | BACKUP (last line) | LOGGING/monitoring.
Small-org priorities (often FREE): tested backups > updates > MFA > unique passwords > antivirus/firewall > least privilege > awareness > encryption.
Zero risk does NOT exist -> manage RISK (proportionate to the stakes) + keep the ability to DETECT and RECOVER.

=== ASSET MANAGEMENT & SERVICES ===
- Asset management = a current INVENTORY (workstations, servers, printers, licences, network). You manage well only what you KNOW.
- ITSM = run IT as structured SERVICES | ITIL = a best-practice framework (ADAPT it, don't apply it to the letter).
- A tool = auto inventory + tickets + knowledge base + licence tracking.

=== DOCUMENTATION ===
- 3 families: INFRASTRUCTURE (network, servers, access) | PROCEDURES (step-by-step) | KNOWLEDGE BASE (solutions).
- Vital for: CONTINUITY (avoid the "bus factor"), EFFICIENCY (reproduce/delegate), RECOVERY, growth.
- SIMPLE and CURRENT > exhaustive and obsolete (wrong docs mislead). Accessible, central, living, concrete.
- Document WHILE you do it, not "later" (which never comes).

=== SPECIALIZING ===
Paths: NETWORK | CLOUD (Azure/AWS/GCP) | CYBERSECURITY | SYSTEMS | + DevOps, databases, management.
- Choose on appetite + aptitude + market. TEST in a lab/VM before committing. A choice is NOT irreversible.
- Certifications: structure learning, validate, add visibility -> BUT do not replace EXPERIENCE and practice. Mind their VALIDITY.

REMINDERS
- Lay a generalist base, then specialize.
- Least privilege everywhere; MFA on accounts.
- Tested 3-2-1 backups + one disconnected copy.
- Treat PROBLEMS, not just incidents.
- Document as you go. Keep learning.