DNS basics
Start here if you're new to DNS.
DNS propagation
Why DNS changes take time, and how to check them.
What is DNS propagation?DNS propagation explained: why DNS changes take time to appear everywhere, the role of TTL and resolver caching, and what really…How long does DNS propagation take?Realistic DNS propagation times for A records, MX records, TXT records and nameserver changes, what makes them slower, and how to…How to check DNS propagationStep-by-step: check DNS propagation with a free online checker, read the results correctly, and verify records yourself with dig…
DNS record types
What each record does, with examples and common mistakes.
Understanding A recordsWhat an A record is, how it points a domain to an IPv4 address, examples, TTL advice, common mistakes, and how to look up the A…Understanding AAAA recordsAAAA records explained: how they map a domain to an IPv6 address, when you need one, what happens when it's wrong, and how to…Understanding CNAME recordsCNAME records explained with examples: how aliases work, the rules (no CNAME at the root, no other records alongside), common…Understanding MX recordsMX records explained: how they route email, what priority numbers mean, examples for common providers, mistakes that stop email…Understanding TXT recordsTXT records explained: how they store SPF, DKIM, DMARC and domain verification values, the 255-character rule, common errors and…Understanding NS recordsNS records explained: how nameserver records delegate a domain, parent vs child NS records, glue records, common problems and how…Understanding SOA recordsThe SOA (start of authority) record explained field by field: primary nameserver, admin email, serial number, refresh, retry,…Understanding CAA recordsCAA records explained: how they restrict which certificate authorities can issue SSL/TLS certificates for your domain, the…
Troubleshooting
Fix websites and domains that won't resolve.
How to change nameserversA safe, step-by-step process for changing your domain's nameservers: export your records, rebuild the zone, handle DNSSEC, update…Why is my website not loading after changing DNS?Website down after a DNS or nameserver change? Work through the eight most common causes — from caching and missing records to…How to fix DNS resolution problemsFix errors like DNS_PROBE_FINISHED_NXDOMAIN, ERR_NAME_NOT_RESOLVED and “server not found”: flush caches, change resolver, check…How to troubleshoot DNS problemsA systematic DNS troubleshooting checklist for website owners and admins: registration, delegation, nameservers, records, DNSSEC,…
Email authentication
SPF, DKIM, DMARC and getting mail into the inbox.
What is an SPF record?SPF explained: how a Sender Policy Framework record authorises mail servers, syntax and examples, ~all vs -all, the 10 DNS lookup…What is DKIM?DKIM explained: how DomainKeys Identified Mail signs email, what selectors are, what a DKIM DNS record looks like, key length…What is DMARC?DMARC explained: how it builds on SPF and DKIM, p=none vs quarantine vs reject, alignment, aggregate reports, a safe rollout plan…How to fix emails going to spamPractical steps to stop your emails landing in spam: fix SPF, DKIM and DMARC, check blacklists, set reverse DNS, and improve…
Blacklists & reputation
Check, understand and clear IP blacklistings.
How to check if your IP is blacklistedFind your mail server's IP address, run a DNSBL blacklist check, understand listed, clean and unavailable results, and know which…How to remove an IP from a DNS blacklistStep-by-step DNSBL delisting: find why the IP was listed, fix the root cause, use each blacklist's removal process, and stop it…