DNS (Domain Name System) is the distributed system that maps domain names—like example.com—to the technical records computers need to find services. When you type a website address or send email, DNS lookups determine where the request should go.
Without DNS, people would need to remember raw network addresses. With DNS, brands use stable names while infrastructure underneath can change carefully via record updates.
Common record types (conceptual)
- A / AAAA — point a host name to an IPv4/IPv6 address
- CNAME — alias one name to another
- MX — mail servers for a domain
- TXT — verifications and email authentication data
- NS — which nameservers are authoritative for the zone
What happens when you visit a site
- Browser asks a resolver for the domain
- Resolver locates authoritative DNS answers
- Records return the hosting target
- Browser connects to the web server
- SSL/TLS secures the session when configured
TTL and propagation
Each record has a TTL (time to live) hinting how long resolvers may cache answers. After DNS changes, some users see updates quickly and others later—often called propagation. Plan cutovers with TTL strategy and verification checklists.
DNS and email
Incorrect MX or authentication TXT records break mail or increase spoofing risk. See SPF, DKIM, and DMARC.
Nameserver vs record edits
Sometimes you change nameservers at the registrar to point to a host’s DNS; sometimes you keep nameservers and edit records in place. Know which model you use before troubleshooting “why didn’t it update?”
Safe cutover checklist
- Inventory existing records (especially MX and TXT)
- Lower TTLs ahead of time when planning a move
- Recreate records at the destination
- Switch and verify web, email, and critical integrations
- Keep a rollback plan
Subdomains for systems
app., api., and mail. hostnames keep architecture clearer than overloading the apex for every service. Plan certificate coverage accordingly.
FAQ
Why is email broken after a website move?
Because MX or authentication records were overwritten during a web-only DNS edit. Always export the full zone before changes.