DNS
A, MX, CNAME and TXT records, TTL and propagation, dig and nslookup commands, subnet masks: what you need to understand and troubleshoot DNS and addressing on a small network. Each article links to the matching tool on the site.
30 articles by topic
October 2026
3 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 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 article
Related tools and cheatsheets
Tags
- ACME
- Active Directory
- AI
- Anthropic
- Audit
- Banking
- Business continuity
- CAA
- Certificates
- ChatGPT
- CIDR
- Claude
- CNAME
- Copilot
- Crédit Mutuel Arkéa
- Cyberattack
- DeepSeek
- Deliverability
- dig
- DKIM
- DMARC
- DNS
- End of life
- ESU
- Exchange Online
- GDPR
- Gemini
- Google Workspace
- Hardware
- Headers
- Hosting
- IMAP
- IoT
- IPv4
- Le Chat
- Let's Encrypt
- Linux
- Logs
- Microsoft 365
- Migration
- Mistral
- MX
- Networking
- nslookup
- OAuth
- OpenAI
- OpenSSH
- Orange
- Outage
- Patch Tuesday
- Patches
- Perplexity
- Phishing
- PHP
- PowerShell
- Privacy
- PXE
- RAM
- RFC 1918
- Samsung
- Search
- Secure Boot
- Security
- SMTP
- SPF
- SSD
- Subnet
- Subnet mask
- Symfony
- TLS
- TTL
- TXT
- UEFI
- Updates
- Virtualization
- Vulnerability
- Windows
- Windows 10
- Windows 11
- Windows Server