Guillaume Richard's blog
Technical notes written along the way: email, DNS, Microsoft 365 / Google Workspace administration and the workstation.
30 articles by topic
November 2026
11 articlesAI at Work: Comparing the Assistants from an IT Technician’s Seat
How I pick an AI assistant for scripts, troubleshooting and documentation: ChatGPT, Claude, Gemini, Copilot, Mistral, DeepSeek and Perplexity compared.
Read the articleChatGPT for an IT Technician: Use Cases, Limits, Pricing and GDPR
ChatGPT in an IT job: scripts, troubleshooting, documentation, what not to paste into it, and the Free, Go, Plus, Pro and Business plans.
Read the articleClaude for an IT Technician: Use Cases, Limits, Pricing and GDPR
Claude in an IT job: scripts, long documents, troubleshooting, privacy, and the Free, Pro, Max, Team and Enterprise plans as of 6 November 2026.
Read the articleCrédit Mutuel Arkéa Cyberattack: What We Know, and What to Do
Crédit Mutuel Arkéa lost around €100M in a cyberattack through a supplier: confirmed facts, open questions, and what customers and businesses should do.
Read the articleDeepSeek for an IT Technician: Use Cases, Limits and GDPR
DeepSeek in an IT job: its appeal through the API, European regulators’ concerns about data, and why I hand it no data.
Read the articleGemini for an IT Technician: Use Cases, Limits, Pricing and GDPR
Gemini in an IT job: Google Workspace, scripts, documents, GDPR, and the Google AI Plus, Pro and Ultra plans in euros as of 6 November 2026.
Read the articleMicrosoft Copilot for an IT Technician: Use Cases, Pricing and GDPR
Microsoft Copilot at work: free Copilot Chat, Copilot Business, access rights, privacy, and per-user prices excluding VAT as of 6 November 2026.
Read the articleMistral (Le Chat, now Vibe): IT Use Cases, Pricing and GDPR
Mistral AI, a French provider: Le Chat now called Vibe, its use for scripts and development, and the Free, Pro and Team plans as of 6 November 2026.
Read the articleOpenSSH and Symfony: the Vulnerabilities of the Week of 2 November 2026
OpenSSH flaw (CVE-2026-123158) on Linux systems without PAM such as Alpine, and Symfony security fixes of 4 November: who is affected and what to update.
Read the articlePerplexity for an IT Technician: Search, Sources and Limits
Perplexity in an IT job: a search that cites its sources, how to check it, what not to paste into it, and its plans in dollars.
Read the articleRAM and SSD Shortage: Why Prices Are Rising, and When to Buy
RAM and SSD prices are rising in 2026 as AI demand (HBM, servers) soaks up memory. What Samsung says, the impact on PCs, and when to buy.
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October 2026
19 articlesCIDR and subnet masks explained: /24, /27 and subnetting
CIDR notation (/24, /27), dotted-decimal masks, usable addresses and subnetting, with checked calculations and a free subnet calculator.
Read the articleDNS records explained: A, MX, CNAME, TXT and the others
What the A, AAAA, CNAME, MX, TXT, NS, SOA, CAA, PTR and SRV DNS records do: examples, classic pitfalls and basic dig and nslookup commands.
Read the articleExchange Online: The End of Password-Based SMTP AUTH, and Your Scanners, Printers and Apps
Exchange Online turns off password-based SMTP AUTH by default at the end of December 2026: find the scanners, printers and apps that depend on it, then migrate.
Read the articleOrange Outage of 21 October 2026: What We Know and How to Protect Yourself
Ten hours without Orange and Sosh mobile service: timeline, announced cause, and concrete measures so an operator outage does not stop a small business.
Read the articleOctober 2026 Patch Tuesday: What to Install First in a Small Organization
October 2026 Patch Tuesday: an exploited Windows Shell flaw, a record number of fixes, two known issues and the end of Windows 11 24H2. The priorities.
Read the articlePHP Flaws CVE-2026-109618 and 109619: What to Do, a Week Later
Two critical remote code execution flaws in PHP, fixed on 21 October 2026. Affected versions, a verified timeline, workarounds and an action plan.
Read the articleReading Email Headers: Received, SPF, DKIM, DMARC
Where to find headers in Outlook, Gmail and Thunderbird, how to read Received, Authentication-Results and DKIM-Signature, and spot spam or spoofing.
Read the articleSecure Boot: the 2011 Certificates Have Expired, How to Check
The 2011 Secure Boot certificates expired in June and October 2026: how to check a PC or server, update firmware, and handle Linux, dual-boot and VMs.
Read the articleSupermarket Fridge Cyberattack in France: What We Know and the Lessons
11 to 12 October 2026: refrigeration controllers hacked in hundreds of French supermarkets. Equipment, cause, losses and measures for any connected device.
Read the articleTLS certificates: 200, then 100, then 47 days of validity
Since 15 March 2026 a public TLS certificate lasts 200 days at most, then 100 days in 2027 and 47 days in 2029. The schedule and how to prepare.
Read the articleUEFI Flaw CVE-2026-97631: One ICMP Packet During PXE Network Boot
A critical EDK II firmware flaw allows code execution before Secure Boot during a PXE boot. Who is affected, what is fixed and how to reduce the risk.
Read the articleWindows Event Log IDs Worth Knowing
The Windows event IDs to watch in a small business: logons (4624, 4625), accounts, groups, lockouts, Kerberos, with PowerShell filters.
Read the articleWindows Server 2016: End of Support on 12 January 2027
Windows Server 2016 support ends on 12 January 2027: inventory, migrating to Server 2025 or 2022, ESU through Azure Arc, and Active Directory.
Read the articleTroubleshooting DNS with dig and nslookup
Query the right server, understand DNS "propagation" and TTL, and spot the most common zone mistakes (apex CNAME, MX, TXT, delegation).
Read the articleEmails Going to Spam or Bounced: A Troubleshooting Method
Read a bounce message, analyze headers, check SPF/DKIM/DMARC, reputation and reverse DNS: a step-by-step approach to find the cause.
Read the articleMigrating to Microsoft 365 or Google Workspace: a Checklist
Inventory, migration method, TTL, MX cutover and checks: the steps that prevent lost emails when you change mail providers.
Read the articleSecuring Microsoft 365 and Google Workspace: Baseline Settings
MFA, admin accounts, legacy authentication, auto-forwarding, external sharing, backup and offboarding: the essential measures for a small business.
Read the articleSPF, DKIM and DMARC: a Configuration Guide
What each DNS record does, ready-to-adapt examples, common pitfalls and a step-by-step rollout plan up to a DMARC reject policy.
Read the articleWindows 10 End of Support: Planning the Move to Windows 11
Hardware requirements, fleet inventory, Extended Security Updates (ESU), Windows 11 lifecycle and a migration plan for a small business.
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