Domains
How DNS Works for Websites and Email
Understand nameservers, website records, mail records and caching before editing your DNS zone.
DNS tells devices where to find services for a domain. Authoritative nameservers hold the zone, while resolvers cache answers for a time. Editing the wrong DNS provider or ignoring cached records can make a correct-looking change appear ineffective.
Practical steps
- Identify the authoritative nameservers before editing records. A domain registrar and DNS host are not necessarily the same service.
- Use A or AAAA records for address mappings and CNAME where an alias is appropriate. Follow the host's instructions rather than replacing unrelated records.
- Keep MX records for mail routing and TXT records for services such as SPF, DKIM and DMARC. Changing website hosting should not automatically replace these.
- Record the old values and TTLs before a planned change. Lowering a TTL in advance can help future changes, but does not erase answers already cached under an older TTL.
Check the result
Query authoritative records and compare results from more than one network. Test the actual service as well as DNS, since a correct address does not prove the destination application is healthy.
Before you proceed
Never guess nameservers or copy another customer's records. Use the settings assigned to your account, and avoid publishing multiple contradictory SPF policies.