DevOps & SRE
Site reliability & DevOps — start with the beginner Linux Fundamentals on-ramp, then the LFCS Linux sysadmin cert and the HashiCorp Terraform Associate (003) infrastructure-as-code cert, each with objective-weighted decks and a recall exam, plus hands-on Linux & Bash labs, CI/CD, networking, and production break-fix troubleshooting.
Watch first
~45mCommand Line Basics for Beginners — Full Course · freeCodeCampThe on-ramp — navigating the shell, files and directories, and core commands before the LFCS-depth Linux lab.~141mLinux Crash Course for Beginners with Labs · freeCodeCampHands-on middle layer — permissions, processes, packages and users with labs, bridging basics to the break-fix scenarios.~367mIntroduction to Linux — Full Course for Beginners · freeCodeCampDeep dive — a broad tour of the filesystem, shell, users/permissions and administration that grounds the LFCS decks.
Start here
Linux Fundamentals (Beginner On-Ramp)30 cards — step 1 of 31Then get hands-on: Linux lab — 36 scenarios.
LFCS — Linux Foundation Certified System Administrator — learning pathThe hands-on Linux sysadmin cert — five domain-weighted decks (106 cards), an 85-question recall exam, and hands-on Linux & Bash labs, verified to the official Linux Foundation domains.HashiCorp Terraform Associate (003) — learning pathThe industry-standard infrastructure-as-code cert — eight objective-aligned decks (258 cards), an 83-question practice exam, and the browser-graded HCL drills for writing real config. Prep at $0.Ansible Automation — learning pathThe agentless config-management & automation tool — eight topic decks (208 cards) across inventory, playbooks, variables & Jinja2, roles, modules, handlers, and vault, plus a practice exam and the browser-graded YAML drills. Learn it at $0.
Flashcard decks
31 decks · 1056 cards · in study orderLFCS cert domains
5 decks · 106 cards2LFCS · Essential Commands (20%)The everyday shell: file & directory operations, finding things (find/locate), text processing (grep/sed/awk/cut/sort/uniq), pipes & redirection, permissions & ownership (numeric and special bits), links (hard vs symbolic), archives & compression (tar/gzip), and globbing.213LFCS · Operations Deployment (25%)The biggest domain: systemd services & targets, the boot process & GRUB, scheduling with cron / at / systemd timers, package management (apt/dnf/rpm/dpkg), kernel modules & runtime parameters (sysctl), process priorities, and SELinux basics.264LFCS · Networking (25%)IP addressing & routing with the `ip` suite (ifconfig is deprecated), persistent config via NetworkManager/nmcli & netplan, hostname & DNS resolution, firewalls (firewalld & nftables/iptables), SSH & key auth, socket/port inspection with `ss`, time sync, and network troubleshooting.225LFCS · Storage (20%)Block devices, partitioning (MBR vs GPT), creating & mounting filesystems, persistent mounts via /etc/fstab (by UUID), LVM (PV→VG→LV) and growing volumes, swap, filesystem resizing (ext4 vs XFS), quotas, RAID basics, and encrypted (LUKS) volumes.216LFCS · Users and Groups (10%)Account & group lifecycle (useradd/usermod/userdel, groupadd), the -aG append trap, password & account aging (passwd/chage), the /etc/passwd, /etc/shadow, and /etc/group files, sudo/privilege via sudoers, and locking/unlocking accounts.16
Core vocabulary
4 decks · 227 cards7Networking FundamentalsPractical TCP/IP fundamentals: IPv4/IPv6 + CIDR/subnetting, TCP vs UDP, the TCP handshake, common ports, DNS + record types, DHCP, NAT/PAT, routing vs switching, VLANs, ARP, ICMP/ping/traceroute, firewalls, L4 vs L7 load balancing, VPNs/tunnels, TLS, and the everyday troubleshooting toolkit (ping/dig/ss/tcpdump/curl).358OSI ModelThe 7-layer OSI reference model, layer by layer: function, PDU, example protocols + devices, encapsulation/decapsulation, OSI vs TCP/IP mapping, and the 'which layer does X operate at?' questions. A fundamentals refresher.209IaC VocabularyVocabulary and concepts for Infrastructure-as-Code work across Terraform, Ansible, Bicep, ARM, Pulumi, CloudFormation, and general IaC theory. Covers state, idempotency, drift, providers, modules, configuration management, CI/CD integration, and the differences between declarative vs imperative tools.6510CI/CD ConceptsContinuous integration and continuous delivery as a discipline. Covers core concepts (build/test/deploy stages, triggers, artifacts, runners, environments), the major tools (GitHub Actions, GitLab CI, Jenkins, Azure DevOps Pipelines), GitOps (Argo CD, Flux, Tekton), deployment strategies (rolling, blue/green, canary, shadow, feature flags), pipeline security (SAST, DAST, SBOM, SLSA, image signing), and release patterns (build-once-deploy-many, semver, trunk-based vs Gitflow).107
Terraform Associate
8 decks · 258 cards11Terraform Associate 003 - IaC Concepts & Purpose of TerraformPlain-language flashcards on infrastructure as code fundamentals and why you would choose Terraform over other provisioning tools.2612Terraform Associate 003 - Basics: Providers, Init & PluginsHow Terraform declares its providers and version requirements, and how terraform init downloads plugins, writes the dependency lock file, and prepares a working directory.3013Terraform Associate 003 - The Core WorkflowLearn the everyday Terraform loop of writing configuration, previewing changes with a plan, and applying them, plus the commands and plan symbols the exam expects you to recognize.3014Terraform Associate 003 - StateHow Terraform state works and how to manage it safely, including remote backends, locking, plaintext secrets, drift, and the state and import commands.3415Terraform Associate 003 - Reading, Generating & Modifying ConfigurationFlashcards covering Terraform Associate 003 objective 8: input variables, outputs, locals, data sources, expressions, built-in functions, meta-arguments, lifecycle, and provisioners.5616Terraform Associate 003 - ModulesLearn how Terraform modules package and reuse groups of resources, how to source and version them, and how to pass data in and out.2617Terraform Associate 003 - CLI Outside the Core WorkflowFlashcards for exam objective 4 covering Terraform CLI commands you use outside the write-plan-apply core loop, such as fmt, import, state, workspaces, console, output, graph, and debugging tools.3018Terraform Associate 003 - HCP Terraform & EnterprisePlain-language flashcards on HCP Terraform (formerly Terraform Cloud) capabilities: remote state, remote runs, the three workflows, workspaces, private registry, Sentinel policies, cost estimation, and governance.26
Ansible
8 decks · 208 cards19Ansible · Fundamentals & ArchitectureCore concepts of Ansible: what it is, its agentless push architecture, control vs managed nodes, idempotency, and how it compares to other automation tools.2420Ansible · Inventory & PatternsAnsible inventory files, groups, host/group variables, ranges, host patterns, connection settings, and dynamic inventory.2321Ansible · Playbooks, Plays & TasksHow Ansible playbooks are structured and executed - plays, tasks, modules, privilege escalation, handlers, and the ansible-playbook CLI.2622Ansible · Variables, Facts & Jinja2How to define and use variables, work with facts and magic variables, capture output with register/set_fact, and template with Jinja2 filters, conditionals, and loops in modern ansible-core.3223Ansible · Roles & CollectionsReusable automation building blocks in Ansible - role structure and precedence, static vs dynamic reuse, meta dependencies, ansible-galaxy, and the FQCN collections model.2424Ansible · Modules & Common TasksCommon ansible.builtin (and a few community) modules plus idempotent task patterns for packages, services, files, commands, and more.2825Ansible · Idempotency, Handlers & Error HandlingDeck covering Ansible idempotency, handlers, changed_when/failed_when, blocks, check mode, tags, delegation, retries, and execution strategies.2726Ansible · Vault, Config & Best PracticesSecuring secrets with ansible-vault, configuring ansible.cfg and precedence, privilege escalation, and production best practices, linting, and testing.24
PostgreSQL
1 deck · 39 cardsSystem design & whiteboard rounds
2 decks · 39 cards28System Design — ML & Infrastructure ScenariosOpen-ended design prompts of the kind asked in platform and ML-infrastructure interviews — model serving at scale, feature stores, real-time pipelines, multi-region and cost/latency tradeoffs. Practise saying the design out loud, not memorising an answer.2529Whiteboard & Design Rounds — the frameworkHow to answer ANY design or whiteboard question: a repeatable framework, what to clarify first, the tradeoffs to name out loud, and how to keep talking when you feel stuck. Delivery, not trivia.14
SRE & production troubleshooting
2 decks · 149 cards30Production Troubleshooting — tabletop drillsStructured triage for 'something is broken' rounds — the framework, the 'what changed?' checklist, and how to narrate your reasoning so you score well before you reach the answer. The gap that sinks otherwise-good interviews.2331SRE & Cloud Deployment — interview question bankA broad recall bank for SRE, cloud-deployment and platform interviews: Kubernetes, Terraform state, Ansible idempotency, CI/CD, networking, observability and reliability practice. Large on purpose — drill it in slices, not one sitting.126
Practice exams
3 setsLFCS Practice ExamA recall-layer practice exam for the LFCS (the real exam is performance-based — the labs are the true practice). Draws 40 questions per attempt from a blueprint-weighted pool (Operations Deployment 25% · Networking 25% · Storage 20% · Essential Commands 20% · Users and Groups 10%), scored at 70% with a 60-minute soft timer. Original 5-choice command/concept MCQs with worked explanations and a per-domain weak-area breakdown. Pairs with the five LFCS decks and the hands-on Linux labs. Progress saves in your browser — no login.Terraform Associate PracticeDraws 40 questions per attempt from an objective-weighted pool across all 9 Terraform Associate 003 objectives, with a missed-question review, worked explanations, and a per-objective weak-area breakdown. HashiCorp does not publish an official percentage cut score, so 70% here is a READINESS BENCHMARK, not the real pass mark. Real exam: ~57 questions in 60 minutes. Progress saves in your browser - no login.Ansible Automation PracticeDraws 40 questions per attempt from a topic-weighted pool across all 8 Ansible areas (fundamentals, inventory, playbooks, variables & Jinja2, roles & collections, modules, control flow & errors, vault & config), with a missed-question review, worked explanations, and a per-topic weak-area breakdown. There is no vendor-neutral Ansible cert with an official cut score, so 75% here is a READINESS BENCHMARK, not a real pass mark. Progress saves in your browser - no login.
Linux lab
liveBash lab
liveTerraform lab
liveAnsible lab
liveObservability lab
liveHCL (Terraform) drills
6 drillsCurated resources
verified July 2026Linux foundations for the beginner on-ramp deck. The cert PATHS in this subject (LFCS, Terraform Associate, Ansible) each carry their own deeper, exam-specific resource lists on their path pages — these are the general "learn Linux and the command line" references.
Linux foundations & the command line
The Linux Command Line (William Shotts) — free bookfree · bookThe classic, complete beginner-to-capable book on the shell — files, permissions, processes, pipes, and scripting. The best single companion to the Linux Fundamentals on-ramp deck.Introduction to Linux (LFS101) — The Linux Foundationfree · officialThe Linux Foundation's own free, self-paced course — the structured foundation the LFCS builds on. Ideal if you're newer to Linux.tldr pagesfree · open sourceCommunity cheat-sheets showing the handful of commands people actually use for each tool — the friendly counterpart to dense man pages.Linux man-pages (man7.org)free · officialThe authoritative online manual pages — the same reference `man` opens, browsable and searchable when you want the exact flags.