Fundamentals
Active Directory
Core concepts of Active Directory and the domain controller: logical structure, trusts, LDAP naming, roaming profiles and group policies.
Analog-to-Digital Converter (ADC)
How an analog-to-digital converter turns a continuous voltage into a digital value, including resolution, quantization steps, measurement resolution, and the formulas to calculate a binary output.
ARP (Address Resolution Protocol)
How ARP resolves IP addresses to MAC addresses within a local network, including local vs. remote delivery, the request/reply process, and the ARP cache.
Bit, Byte & Unit Conversions
Bit, Byte & Kibi Basics
Databases
5 items
DHCP
How DHCP automatically assigns IP configuration to clients, including the DORA process, leases, scopes, options, reservations, relay agents and failover.
DNS
How the Domain Name System resolves names to IP addresses: hierarchy and FQDN, zones and record types, recursive vs. iterative queries and caching.
Electrical Units – Power, Voltage, Current, and Energy
The relationship between power (P), voltage (U), current (I), resistance (R), and electrical work/energy (W). Including the power triangle, Ohm's law, and kilowatt-hours.
Encryption and Digital Signatures
Overview of symmetric and asymmetric encryption, hash functions, and digital signatures.
File Paths
Absolute and relative paths in a filesystem. How they differ and the special path components `/`, `.`, `..` and `~`.
Filesystem Types
Overview of common filesystem types (FAT32, exFAT, NTFS, ext4, APFS, btrfs) and their typical use cases, limits and platform support.
IPv6 (Internet Protocol Version 6)
How IPv6 addresses are structured, compressed, and expanded, including the most important reserved addresses (loopback, link-local), the unicast/multicast/anycast types, and address scopes.
JSON
JSON conventions: file naming, key naming, and comparison of JSON, JSONC, and JSON5
Name Resolution
Why name resolution is needed and an overview of the common systems for Windows and Linux networks: DNS, LLMNR, NetBIOS and mDNS.
NAT
How NAT translates private IP addresses to public ones, including PAT/overloading and port forwarding.
OSI Model
The 7-layer OSI reference model: an overview of each layer's role, responsibilities, and common protocols.
Frequency (Hz) and Pulse-Width Modulation (PWM)
What frequency in Hertz means, and how pulse-width modulation uses a duty cycle to approximate analog output levels with a purely digital signal, including the period, frequency, and duty-cycle formulas.
RAID
Overview of RAID levels and their trade-offs between performance, redundancy, and storage efficiency.
Raspberry Pi Overview
A practical overview of the Raspberry Pi: its GPIO pins, the difference between sensors and actuators, how a breadboard works, and what the connections of common components such as an LED, a temperature sensor, and a buzzer mean.
Regular Expressions
Overview of regular expression syntax, character classes, quantifiers, anchors, groups, lookaround, and common patterns.
IT Security Goals
The four core IT security goals, confidentiality, integrity, availability, authenticity, and what they mean in practice.
SI Prefixes
Common SI (metric) prefixes and their multipliers, from pico to tera, used to scale units like meters, grams, seconds, volts, watts, and hertz.
Subnetting (IPv4)
Subnetting Basics, Calculations & Examples (IPv4)
UML
2 items
WireGuard
Overview of WireGuard: a modern and fast VPN protocol using state-of-the-art cryptography.