What Is DNS and How Does It Work?

DNS stands for Domain Name System. It is the system that helps browsers, email servers and other internet services find the correct destination for a domain name. Without DNS, visitors would need to remember IP addresses instead of simple names like example.co.uk.

DNS is one of the most important parts of getting a website online, but it is also one of the most confusing for beginners. Once you understand the basics, domain setup, website migrations, email hosting and troubleshooting become much easier.

How DNS works in simple terms

When someone types your domain name into a browser, the browser needs to find the server that hosts your website. DNS provides that answer. It checks the domain records and returns the correct IP address or destination.

The process normally happens quickly in the background. Visitors do not see the lookup; they simply see the website load. But if DNS is wrong, the website may not load, email may fail or visitors may be sent to the wrong server.

Nameservers and DNS records

Nameservers are responsible for holding or pointing to the DNS records for your domain. When you change nameservers, you are changing where the domain's DNS is managed. This is common when moving a domain to a new host or centralising DNS management.

DNS records are the individual instructions. Different record types do different jobs, and it is normal for a domain to have several records at once.

• A record: points a domain or subdomain to an IPv4 address.
• AAAA record: points a domain or subdomain to an IPv6 address.
• CNAME record: points one hostname to another hostname.
• MX record: tells email systems where to deliver mail.
• TXT record: often used for verification, SPF, DKIM and DMARC.

DNS and web hosting

For your website to load from your hosting account, the domain needs to point to the correct server. This is usually done with nameservers or an A record. If the domain points to the wrong IP address, the visitor may see an old site, a default server page or an error.

This is why DNS is important during migrations. You can upload the website correctly, but the public domain will not use the new hosting until DNS points to it.

DNS and email hosting

Email uses DNS too. MX records tell other mail servers where to deliver messages for your domain. TXT records help prove that your mail is legitimate and reduce the chance of messages being treated as spam.

If you move hosting but forget about email DNS, the website may work while email stops. Always check MX, SPF, DKIM and DMARC records when changing DNS for a business domain.

What is DNS propagation?

DNS changes are not always visible everywhere instantly. Different networks and resolvers may cache old records for a period of time. This delay is often called DNS propagation.

Propagation can make testing confusing because one device may see the new server while another still sees the old one. This is normal after DNS changes and is one reason to keep the old hosting active during a move.

Common DNS mistakes

• Changing nameservers without recreating important email records.
• Pointing the root domain but forgetting the www subdomain.
• Using a CNAME where an A record is required.
• Removing TXT records needed for email verification.
• Expecting DNS changes to appear instantly everywhere.

Final thoughts

DNS is the connection layer between your domain, website and email. You do not need to become a DNS expert, but understanding the basics can save hours of confusion when launching a site, moving hosting or fixing email problems.