DNS
30 articles by topic
October 2026
4 articlesDNS 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 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 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 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.
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