A directory for service names
DNS lets a domain name point to services without requiring people to remember an IP address. Different record types answer different questions, such as where a website is hosted or which mail server receives email.
Know the records you change
A and AAAA records map names to IPv4 and IPv6 addresses. CNAME creates an alias. MX routes mail. TXT can prove ownership or publish email policy. Nameservers identify the provider that publishes the authoritative zone.
Why changes take time
Resolvers cache answers based on TTL values. A change may become visible at different times for different users. Lowering TTL in advance can reduce some transitions, but it does not eliminate every cache or provider delay.
Make a reversible change
Save the existing zone, confirm which service depends on each record, and update one purpose at a time. For a nameserver change, build the full new zone before switching authority.