DNS lookup explained

What DNS lookup checks

A DNS lookup asks name servers for records attached to a domain. If a website does not load, email is not delivered, or a verification record is missing, DNS is usually one of the first systems to inspect. DNS changes can also take time to appear everywhere because resolvers cache results according to TTL values.

• A records point a domain to an IPv4 address.
• AAAA records point a domain to an IPv6 address.
• CNAME records alias one name to another hostname.
• MX records define which servers receive email.
• NS records show the authoritative name servers.
• TXT records often store SPF, DKIM, DMARC or service verification data.

When DNS lookup helps

Use DNS lookup when moving a domain to new hosting, confirming a CDN setup, debugging email delivery, checking whether a domain points to the right server, or verifying that a TXT record has been published. Comparing A and AAAA records also helps find cases where IPv4 works but IPv6 is misconfigured.