DNS
Change nameservers safely without breaking email or subdomains
A nameserver change can affect every service under a domain, not just the website. Email, verification, APIs, subdomains, DKIM selectors, and third-party services can fail if their records are missing from the new authoritative zone.
Export or inventory the complete existing zone
Record A, AAAA, CNAME, MX, TXT, SRV, CAA, DKIM, verification, and other records that are actually in use. Pay attention to subdomains that are easy to overlook because nobody visits them manually.
Build the new zone before changing delegation
Create the records at the destination and query the new authoritative nameservers directly. The new zone should be correct while the old nameservers are still serving production.
Change the registrar delegation only when the destination answers correctly
Record the old nameservers and the exact change time. During cache transition, test website and email from multiple resolvers and keep both DNS services available long enough for stale delegation to age out.
Do not combine unrelated migrations without a reason
A registrar transfer, nameserver move, web-host move, and mail-provider move can be separate operations. Staging them reduces the number of possible causes if something fails.