--- title: "What is DNS? A practical guide for business owners" url: https://resahost.net/en/guides/what-is-dns/ canonical: https://resahost.net/en/guides/what-is-dns/ language: en description: "Learn what DNS does, how A, MX and TXT records work, where to change them and how to investigate website or email failures without guessing." author: ResaHost author_url: https://resahost.net/en/contact/ related: - "Domains Choose an Available Domain Name for Your Business Read guide → — https://resahost.net/en/guides/choose-an-available-domain-name/" - "Domains What Is a Domain Name? A Guide for Business Owners Read guide → — https://resahost.net/en/guides/what-is-a-domain-name/" --- Domains 7 min read · Updated 08/2026 # What is DNS? A practical guide for business owners DNS, the Domain Name System, connects names such as `example.com` with information about the services behind them. It lets customers use a memorable address while the underlying website or email infrastructure can change. You do not need to become a network engineer to manage a business domain. You do need to know who controls its records, what a proposed change affects and how the result will be checked. ## The directory behind the address When a browser needs your website's address, a DNS resolver looks up the answer or uses a cached copy. Authoritative nameservers publish the records for your domain. The browser then connects to the relevant service. DNS does not contain the website itself. Buying a domain and adding a record will not create pages, configure HTTPS or set up a mailbox. These are separate services connected through the records. The [domain, DNS and SSL overview](https://resahost.net/en/guides/domains-dns-and-ssl-explained/) explains the complete route in plain English. ## The record types you will encounter | Type | What it does | Business example | | --- | --- | --- | | A | Points to an IPv4 address | Your main website server | | AAAA | Points to an IPv6 address | An IPv6-enabled website destination | | CNAME | Makes one hostname an alias of another | A hosted support portal | | MX | Identifies incoming mail servers | Delivery to your business mailbox service | | TXT | Publishes text used by other services | Domain verification and email policies | | NS | Identifies authoritative nameservers | The service managing your DNS zone | | SOA | Supplies zone administration information | Values generally managed by the DNS provider | A CNAME is a DNS alias, not an HTTP redirect to another page. The destination application still needs to recognise the hostname and serve the appropriate certificate and content. ## Registrar and DNS provider may be different The registrar handles your domain registration. Your DNS provider publishes the zone. If the domain uses another provider's nameservers, editing a zone in the registrar's unused DNS editor will have no effect. Check the nameserver delegation before making changes. Keep the authoritative provider's account details, support contact and an export of the records available to authorised staff. ResaHost's [domain service](https://resahost.net/en/services/domains/) can bring registration and DNS administration into one support relationship where agreed. ## Why your website may not open A missing or incorrect record is one possible cause. An expired registration, broken delegation or DNSSEC validation problem can also stop resolution. A browser's DNS error is a clue to investigate, not proof that hosting hardware failed. Check registration status and the relevant records against the intended destination. If DNS resolves correctly, continue to the connection, certificate and application. Do not keep changing DNS when the actual error is a broken page or database. ## Why email may go to the wrong place MX records route incoming mail. During a website move, preserve the existing mail setup unless email is intentionally moving too. Default records at a new host may not match the service your team uses. A “user unknown” bounce can also mean a missing mailbox or alias at the destination. Keep the full error message and check the recipient configuration as well as DNS. The [domain-to-email connection guide](https://resahost.net/en/guides/connect-your-domain-to-email/) gives a safe sequence for changes. ## What DNS propagation really means Resolvers cache answers according to TTL values. Lowering a TTL before a planned move can shorten the period during which an old answer remains cached, but previously cached records retain their earlier lifetime. There is no guaranteed worldwide refresh at exactly five minutes or exactly 48 hours. Delegation, negative caching and client behaviour can also affect observations. Compare authoritative answers with the resolver a customer is using, and retain the old service until the transition has been verified. ## Security settings serve different purposes SPF, DKIM and DMARC publish information used for email authentication. They help address forged sending identities but do not prevent every phishing message or compromised account. DNSSEC validates signed DNS data; it does not encrypt the website or replace application security. Follow the [DNSSEC configuration guide](https://resahost.net/en/guides/dns-settings-and-dnssec/) before enabling signing or changing nameservers. A short change log and a clear recovery plan are more useful than a collection of unexplained settings copied from another domain. Your website, taken care of. Hosting, domain, email and security in one agreement — from €69/month, excluding VAT. Choose hosting ![Olli Junes: Founder and CEO of ResaHost](https://resahost.net/assets/team/ollijunes.webp) Author Olli Junes: Founder and CEO of ResaHost Founder and CEO · ResaHost, Finland @resacolli LinkedIn ## Read next Domains ### Choose an Available Domain Name for Your Business Read guide → Domains ### What Is a Domain Name? A Guide for Business Owners Read guide →