Reading DNS records: from A to TXT.
A practical introduction to DNS records for website and email troubleshooting.
DNS is the internet’s address book
DNS helps resolve a domain name into records. A records hold IPv4 addresses and AAAA records hold IPv6 addresses. A domain can have several addresses; load balancing, CDNs and regional routing can produce different answers from different resolvers.
Email and verification records
MX records direct incoming email, with lower preference values tried first. TXT records carry verification data and policies. SPF identifies authorized senders, DKIM supports signature verification, and DMARC defines alignment and failure handling. The presence of a TXT record alone does not guarantee email delivery.
Why does TTL matter?
TTL is the number of seconds a DNS answer may remain cached. After an update, cached answers can persist until their existing lifetime ends. Users may therefore see the change at different times. A low TTL increases query frequency; it does not fix an incorrect record.
Where should troubleshooting start?
Check the exact name and record type first. A and AAAA help inspect web addressing; MX helps inspect mail routing. An empty answer can mean only that the requested record type is missing. NXDOMAIN means the queried name was not found. Astrotor queries Cloudflare 1.1.1.1; one resolver’s response does not prove every network sees the same answer.