What is DNS?
The Domain Name System is the internet's address book. It translates a domain name that people type, like example.com, into the information computers actually need — an IP address to connect to, a mail server to deliver email to, or a text record used to prove ownership of the domain.
What each record type means
- A — points a domain to an IPv4 address.
- AAAA — points a domain to an IPv6 address.
- MX — specifies which mail servers handle email for the domain, and in what order.
- TXT — holds arbitrary text, commonly used for domain verification and email authentication (SPF, DKIM, DMARC).
- NS — lists the authoritative nameservers responsible for the domain.
- CNAME — aliases one domain name to another.
Why DNS changes take time to show up
Every DNS record has a TTL (time to live), shown in seconds in the results above. Resolvers around the internet cache a record for that long before checking again. That's why a DNS change — like pointing a domain to a new server — can take anywhere from a few minutes to 48 hours to be visible everywhere, depending on the TTL that was set before the change and how aggressively different resolvers cache.
Common issues this tool can help you catch
- A missing or incorrect MX record, which causes email to bounce.
- An A record still pointing at an old server after a migration.
- Missing SPF/DKIM TXT records, which can cause outgoing email to land in spam.
- NS records that don't match your registrar, which usually means DNS isn't being managed where you think it is.