What Is DNS? A Beginner’s Guide for UK Business Owners

Short answer: DNS is the address book of the internet. It turns a name people can remember, like yourbusiness.co.uk, into the numeric address of the server your website actually lives on. When someone says “it is probably a DNS issue”, they usually mean the address book is pointing at the wrong place, or has not caught up with a change yet.

If you have ever set up a website or email address and been told to “update your DNS” or “point your nameservers”, you might have nodded along while having very little idea what that actually meant. You are far from alone. DNS is one of those pieces of internet infrastructure that quietly works in the background, and most people never need to think about it, until the moment they do.

This guide explains DNS in plain English, using simple analogies rather than technical jargon, so that the next time someone mentions nameservers, A records, or propagation, you will know exactly what they are talking about and why it matters for your website and email.

What Does DNS Actually Stand For?

DNS stands for Domain Name System. Its job is to translate human-friendly website addresses, like switchweb.co.uk, into the numerical addresses that computers actually use to find each other on the internet, known as IP addresses.

Without DNS, you would need to remember a string of numbers for every website you wanted to visit, rather than a memorable name.

The Phonebook Analogy

The easiest way to understand DNS is to think of it as a phonebook for the internet.

Imagine you want to call a friend. You do not need to remember their phone number, because you look up their name in your phone’s contacts, and it connects the call for you. DNS works in a similar way: you type a website address into your browser, and DNS looks up the correct “number” (the IP address of the server hosting that website) and connects you to it.

When people talk about “DNS settings”, they are really talking about entries in this phonebook, telling the internet where to find your website, your email, and other services associated with your domain.

The Building Blocks: Records, Nameservers and Zones

To understand how DNS works in practice, it helps to know three key terms.

DNS records

A DNS record is a single entry in the phonebook. Each record tells the internet something specific about your domain, such as where your website is hosted, or where emails sent to your domain should be delivered. There are several types of DNS record, which we will cover below.

Nameservers

A nameserver is the system that actually stores and serves up your DNS records, the “phonebook” itself. Your domain is configured to use specific nameservers, usually provided by either your domain registrar or your hosting provider.

When you change your nameservers, you are essentially telling the internet, “from now on, look at this phonebook for information about my domain”, rather than changing individual entries one by one.

DNS zone

A DNS zone is the collection of all the DNS records for your domain, stored together. When you log into your domain registrar or hosting control panel to “manage DNS”, you are usually viewing and editing your domain’s zone.

The DNS Records You’re Most Likely to Encounter

There are many types of DNS record, but for most small business websites, a handful come up again and again.

A record

An A record points your domain (or a subdomain, such as www) to a specific IP address. This is the most fundamental record for making your website appear when someone types in your domain name. The AAAA record does the same job for newer IPv6 addresses.

CNAME record

A CNAME (Canonical Name) record points one domain or subdomain to another domain name, rather than directly to an IP address. This is often used for things like pointing www.yourbusiness.co.uk to yourbusiness.co.uk, or connecting third-party services such as email marketing platforms.

MX record

MX (Mail Exchange) records tell the internet where emails sent to your domain should be delivered. If your MX records point to the wrong place, or are missing, emails sent to your domain will bounce or fail to arrive, even if your website is working perfectly.

TXT record

TXT records store text information related to your domain, often used for verification purposes (proving you own a domain to a third-party service) or for email authentication settings such as SPF, DKIM and DMARC, which help prevent your emails from being marked as spam. Our guide to SPF, DKIM and DMARC explains what each of those does.

NS record

NS records name the authoritative nameservers for your domain. Changing these hands control of the entire zone to a different provider, which is a bigger move than changing any individual record, as the next section explains.

Nameservers Versus Individual Records

This is the single most useful distinction to understand, because it determines how much can go wrong when you make a change.

Changing nameservers moves the entire address book to a new provider. Everything, website and email, is then read from the new provider’s records. If those records are not set up correctly first, everything breaks at once. It is the simplest option and the one most hosts will recommend, because they then manage everything for you.

Changing an individual A record moves only the website and leaves email exactly where it is. More surgical, lower risk, but you keep managing DNS wherever it currently sits.

Neither is wrong. The choice depends on whether you want one provider handling everything or would rather keep email separate. Our guide to pointing your domain at new hosting walks through both routes, and if you want to keep a site on a website builder while moving only your mail, see using Switchweb for email only.

Why Does DNS Matter for Your Website and Email?

DNS sits quietly behind almost everything related to your online presence:

• Your website appearing correctly – A records and CNAME records determine which server people are sent to when they visit your domain
• Your email working properly – MX records determine where emails to your domain are delivered, and TXT records help ensure those emails are trusted rather than marked as spam
• Connecting third-party tools – many services, from email marketing platforms to booking systems, require you to add specific DNS records to verify ownership or connect properly
• Moving to a new host – when you switch web hosts, DNS is usually how your domain gets pointed to your new hosting account

If something seems wrong with your website or email, particularly after making changes to hosting, domains, or third-party services, DNS is often the first place to look.

What Is DNS Propagation, and Why Does It Take Time?

One of the most confusing aspects of DNS for non-technical users is the delay between making a change and seeing it take effect. This delay is called propagation.

Here is why it happens: DNS information is not stored in just one place. Instead, copies of DNS records are cached (temporarily stored) by internet service providers, networks, and devices all over the world, to make lookups faster. Each cached copy has an expiry time, known as TTL (Time To Live), measured in seconds. A TTL of 3600 means an hour. A TTL of 86400 means a day.

When you make a DNS change, it can take anywhere from a few minutes to up to 24 to 48 hours for that change to fully propagate, as different caches around the world expire and refresh with the new information. During this time, some visitors might see your old website or the new one, depending on which cached copy their device or network is using. This is also why a change can look like it worked for you and not for a colleague: you are hitting a cache that has already refreshed, and they are hitting one still holding the old answer. Nothing is broken.

The trick that makes propagation fast

Lower your TTL a day before you plan to make a change. Drop it to 300 seconds, wait for the old, longer TTL to expire, then make the change. Propagation then takes minutes rather than up to 48 hours, and you have a fast route back if something turns out to be wrong. Put the TTL back up once everything has settled.

This one step removes most of the anxiety from DNS changes, and almost nobody does it.

What this means in practice

• After changing nameservers or DNS records, do not panic if things do not update instantly
• Avoid making multiple changes in quick succession, as this can make troubleshooting harder while everything is still propagating
• If possible, make DNS changes during quieter periods (such as evenings or weekends) to reduce the impact of any temporary inconsistency
• Write down the existing records before you change anything, so you always have a way back

Common DNS Scenarios for Small Businesses

Setting up a new website

When you register a new domain and set up hosting, you will typically need to either change your nameservers to point to your hosting provider, or add specific A records pointing to your hosting provider’s server, depending on how your provider’s setup process works.

Setting up business email

Whether you use email hosting included with your web hosting, or a separate service like Google Workspace or Microsoft 365, you will usually need to update your domain’s MX records to point to wherever your email is actually hosted. If your website and email are hosted in different places, this is an important distinction to get right.

Moving to a new host

When switching web hosts, DNS is the mechanism that redirects your domain from your old host to your new one. Getting this right, and understanding that it will not happen instantly, is key to a smooth transition with minimal downtime. Our guide to moving your website to a new host sets out the order to do things in.

Connecting third-party tools

Many services, from email marketing platforms to live chat tools, ask you to add a specific DNS record (often a TXT or CNAME record) to verify that you own the domain, or to connect the service properly to your domain.

When Something Looks Like a DNS Problem

The symptom usually tells you where to look first.

• Website down, email fine. Almost certainly the A record or the web server, not DNS as a whole. If DNS were entirely broken, email would fail too.
• Email down, website fine. Look at the MX records first.
• Works for some people, not others. Caching. Wait for the TTL to expire.
• Works with www but not without, or the reverse. One of the two is missing a record. They are configured separately.
• Certificate warning after a move. DNS is probably fine and the SSL certificate has not issued on the new server yet.
• Nothing resolves at all. Check the domain has not expired before assuming a DNS fault. Our guide to what happens when a domain expires covers that timeline, and if you are seeing a “this site can’t be reached” or DNS_PROBE_FINISHED_NXDOMAIN error, our diagnosis guide for that specific error walks through the causes in order.

If you are not sure who currently controls the DNS for a domain, our guide to finding out who hosts a website shows how to check the nameservers yourself.

Frequently Asked Questions

What is the difference between a domain registrar and a DNS provider?

A domain registrar is the company you registered your domain name with. A DNS provider is whoever is actually hosting your DNS zone (your collection of DNS records). These are often the same company, but not always; for example, you might register your domain with one company but use your hosting provider’s nameservers to manage DNS.

How long does DNS propagation actually take?

Usually a few hours. The worst case is governed by the TTL that was in place before you made the change, which is why lowering it in advance helps so much. Claims of “up to 72 hours” are mostly a legacy of much longer default TTLs than anyone uses today.

Can I change DNS records myself?

In most cases, yes, with two precautions: write down the existing records first, and lower the TTL in advance. Almost every DNS mishap is quickly recoverable if you know what the settings were beforehand. Incorrect records can take your website or email offline until corrected and propagated, so work carefully.

Can I host my website and email with different companies?

Yes, and plenty of businesses do. The A record points at the website host and the MX records point at the email provider. They are independent of each other.

How do I know if a DNS change has worked?

There are free online DNS lookup tools that let you check the current value of a domain’s DNS records from various locations around the world. These can help confirm whether a change has propagated, though it is normal for results to vary slightly depending on location during the propagation period.

Why does my website work but my email doesn’t (or vice versa)?

This is usually a sign that different DNS records are pointing to different places, which is completely normal. Your website’s A record might point to your hosting provider, while your MX records for email point somewhere else entirely, such as a dedicated email hosting service. Each needs to be correct independently.

What is the difference between DNS and a domain transfer?

A domain transfer moves who you pay and who administers the registration. A DNS change moves where the domain points. You can do either without the other. Our guide to transferring a .co.uk domain and IPS tags covers transfers.

Getting DNS Right When You Switch or Set Up Hosting

DNS changes are one of the most common sources of confusion when setting up a new website or moving to a new host, mainly because of the propagation delay and the number of different record types involved.

At Switchweb, our team handles the DNS side of setting up new hosting accounts and migrations, and our UK-based support is on hand if you need help understanding or updating your domain’s DNS settings. If you are setting up a new website or planning a move, our domains page and web hosting plans are a good starting point.

For everything else about domains, including extensions, pricing, transfers and expiry, see our complete guide to UK domain names. If you are planning a move, our guide to moving your website to a new host sets out the order to do things in.