The Domain Name System (DNS) is the internet's directory: it turns a domain name such as example.com into the addresses and settings that computers use to find your website, deliver your email and verify your services. If a record is missing or wrong, the website may not load and email may not arrive, even when the servers themselves are working.
How DNS works in plain language
Your domain has a set of DNS records, often called a zone. Each record answers one question, such as "which server hosts the website?" When a visitor opens your site:
- The browser asks a resolver, usually run by the visitor's internet provider or a public DNS service.
- The resolver finds the authoritative nameservers that hold your records.
- The nameservers return the record, for example the IP address of your web server.
- The resolver caches the answer for a set time.
Registrar, DNS host and web host are different roles
Many SMEs buy everything from one provider, so the roles blur. Before a move, it helps to know which is which:
- Domain registrar: where the domain is registered and renewed. The registrar account also sets which nameservers the domain uses.
- DNS host: the provider whose nameservers hold your records. This may be the registrar, your web host, a CDN provider or a separate DNS service.
- Web host: the server or platform that stores and runs the website.
- Email provider: the service that receives and sends mail for your domain. It is often separate from the web host.
Changing one of these does not automatically change the others. A new web host does not move your email.
Common DNS record types
- A: points a name to an IPv4 address, for example the web server for example.com.
- AAAA: the same job for an IPv6 address.
- CNAME: makes one name an alias of another hostname, for example www pointing to a platform or CDN hostname. A CNAME generally cannot sit alongside other records with the same name.
- MX: lists the mail servers that accept email for the domain, with a priority value for each.
- TXT: free text used for domain verification and email authentication. SPF lists which services may send email for the domain; DKIM publishes a key that receivers use to check message signatures; DMARC tells receivers what to do when those checks fail and where to send reports.
- NS: names the nameservers that are authoritative for the domain or a subdomain.
TTL and propagation
Every record has a TTL (time to live), in seconds, that tells resolvers how long they may cache it. After a change, some visitors may still reach the old destination until their resolver's cached copy expires. This delay is usually called propagation. Changing nameservers can take longer to settle than editing one record. A common approach is to lower the TTL on records you plan to change ahead of a migration, at least as far ahead as the current TTL, then raise it again once the move is stable.
Typical problems when moving a website or email
- Wrong or missing MX records: email bounces or goes to the old mailbox after a move.
- Records not copied when nameservers change: moving DNS hosting without recreating every record can drop MX, TXT or subdomain records.
- Editing records at the old provider: only the DNS host that the nameservers point to is live. Changes made elsewhere have no effect.
- Forgotten domain renewal: if the domain expires, the website and email can both stop.
- Lost registrar login: if the account belongs to a former employee or vendor, recovering control can take time.
- Certificates not ready: the new host may need DNS to point to it before it can issue an SSL certificate.
Illustrative example: A company moves its website and switches nameservers to the new provider, but only recreates the A and CNAME records. The website works, yet incoming email stops because the MX records were left at the old DNS host.
A short pre-migration checklist
- Confirm who owns the registrar account, that you can log in, and when the domain renews.
- Find out which provider currently hosts DNS by checking the nameservers.
- Export or record every existing record, including MX, TXT and subdomains.
- Agree which records will change, who changes them, and when.
- Lower the TTL in advance on records that will change.
- After the change, test the website, forms, email in both directions and the certificate. Keep the old service running until traffic has moved.
Once the move is done, website monitoring can help you spot it early if the site or certificate stops working. If you are planning a new site or a move, see how technine.io handles website and web app development.
Frequently asked questions
Is DNS the same as my domain name?
No. The domain name is what you register. DNS records say where that name points for the website, email and other services.
Do I need to change DNS when I change web host?
Usually you update at least the A or CNAME records for the website. You do not need to move DNS hosting or touch the email records unless you are also changing those services.
Do SPF, DKIM and DMARC guarantee my email reaches the inbox?
No. They help receiving systems check that a message really comes from your domain. Delivery also depends on the sending service, content and the receiver's filtering. Your email provider can give the exact records to publish.