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OSI and TCP/IP Models — What Every Developer & Sysadmin Should Know
Practical comparison of the 7-layer OSI model and 4-layer TCP/IP model, packet encapsulation, and bottom-up network debugging techniques.
IP Subnetting and CIDR in 10 Minutes — A Practical Guide
Complete beginner guide to IPv4 addresses, CIDR prefix notation, calculating usable hosts, subnet masks, RFC 1918 private ranges, and CLI tools.
Proxmox VE Getting Started — Installation, Storage, VMs, and LXC
Complete beginner guide to Proxmox VE bare-metal virtualization, ZFS vs LVM storage, launching KVM virtual machines, and managing LXC containers via CLI.
Transfer a Domain Without Downtime — Complete Migration Guide
Step-by-step guide to transferring domain names between registrars with zero downtime, EPP Auth-Codes, ICANN 60-day rules, and DNSSEC handling.
Nameserver Delegation and Glue Records — Resolving the Chicken-and-Egg Problem
Complete beginner guide to DNS zone delegation, in-bailiwick nameservers, glue records, avoiding lame delegations, and CLI verification tools.
DNS Records Overview — The Definitive Beginner Guide
Complete reference to all fundamental DNS record types (A, AAAA, CNAME, MX, TXT, NS, SOA, SRV, CAA, PTR), zone syntax, and inspection commands.
DNS A and AAAA Records — Pointing Domains at IP Addresses
Complete beginner guide to IPv4 A records and IPv6 AAAA records, dual-stack configurations, TTL tuning strategies, and CLI verification with dig.
CNAME Aliases — When and How to Use Canonical Name Records
Complete beginner guide to CNAME DNS records, resolution mechanics, why CNAME breaks the zone apex, ALIAS flattening, and the trailing dot rule.
MX Records and Email Deliverability — The SPF, DKIM, and DMARC Trinity
Complete beginner guide to routing incoming email with MX records and achieving 100% inbox delivery using SPF, DKIM, and DMARC authentication.
TXT Records — SPF, DKIM, and DMARC Syntax Masterclass
Complete beginner guide to writing, parsing, and debugging SPF, DKIM, and DMARC TXT records, understanding qualifiers, tags, and avoiding the 10-lookup limit.
DNSSEC Basics — Cryptographic Chain of Trust Explained
Complete beginner guide to DNSSEC, preventing DNS spoofing and cache poisoning, understanding DS, DNSKEY, and RRSIG records, and verifying with dig.
Debugging DNS with dig, host, and nslookup — Complete Sysadmin Toolkit
Master DNS troubleshooting with dig, host, and nslookup, trace root-to-leaf resolution, understand RCODE errors (NXDOMAIN, SERVFAIL), and diagnose cache delays.
Self-Hosting Authoritative DNS with example-dns
Complete beginner guide to running authoritative nameservers, Primary-Secondary replication, AXFR zone transfers, TSIG security, and the example-dns architecture.
Linux Filesystem Permissions — rwx, chmod, chown, and sudo Hygiene
Complete beginner guide to Linux file permissions, user/group ownership, chmod and chown commands and flags, umask, and safe sudo rules.
SSH Hardening — Keys, sshd_config, and Brute-Force Protection
Complete step-by-step guide to securing SSH access on Linux servers using Ed25519 keys, disabling passwords, hardening daemon configuration, and testing.
systemd Services and Timers — systemctl Survival Guide
Complete beginner guide to managing Linux background services, writing custom systemd unit files, viewing journalctl logs, and replacing cron with timers.
btop — Modern Terminal Resource Monitor
Complete beginner guide to btop, monitoring CPU cores, memory, swap, disk I/O, network bandwidth, process inspection, and sending kill signals from your terminal.
tmux — Terminal Multiplexer for Persistent SSH Sessions
Complete beginner guide to tmux, managing persistent sessions across SSH disconnects, splitting terminal panes, keyboard shortcuts, and configuration.
Nginx — High-Performance Web Server & Reverse Proxy
Install, configure, and operate Nginx on Linux for serving static sites, proxying application servers, and managing SSL/TLS certificates.
curl — Command Line HTTP Client & API Debugger
Complete beginner guide to curl, testing REST APIs, inspecting HTTP response headers, verifying SSL/TLS certificates, and debugging response timing with command flag breakdowns.