You shift a site to a new host on a Friday. By Monday the pages load, but your email has stopped arriving. Between the domain name you pay for annually and the server hosting the site, a short list of text entries decides where every visitor and every message goes. Most explanations of DNS reach for the phonebook analogy. It’s accurate, but not much use at four on a Friday afternoon.
What DNS does when someone types your address
Every server on the internet has a numeric IP address, but people remember words. The Domain Name System sits between the two as a translation layer. When a customer types your domain into a browser, their internet service provider asks a chain of servers which machine holds the site. It starts at a root nameserver, which sends it on to the server for your top-level domain. That one names the authoritative server publishing your records.
The answer is held on the way. Your browser keeps a copy for a while, your computer holds one, and your provider’s DNS resolver holds one for everyone on its network. That DNS cache is why a site loads faster the second time you visit. It’s also why a change you made an hour ago is live for you but invisible to a colleague on a different network.
The records a small business touches
A DNS zone is the file holding every record for a domain. Most of it never needs your attention. Four kinds of record account for nearly everything a small business changes.
An A record points a name at the IP address of a server. Your bare domain and your www name each need one, and when you move host this is the record that moves with you. A CNAME record points one name at another name instead of at an address, which suits a subdomain such as shop.yourbusiness.co.uk that should follow the main name wherever it goes.
An MX record points to the servers that take email for your domain. Each has a preference number, with the lowest one tried first. That’s how you set up a backup server. A TXT record stores plain text for other systems to read. SPF and DKIM live there. DMARC sits at its own _dmarc name. Google or Microsoft might ask you to add one to show you own the domain.
Type out the entries provided by your other service character by character. A single mistake in an SPF or DMARC record won’t trigger an error. It alters how mail servers handle your messages, and you only notice when a customer complains their invoice ended up in junk. Our KB covers setting up a DMARC record in cPanel if that is the record you are looking at.
Who holds your DNS and who can change it
Three players are usually involved in a single domain, and that’s where things get confusing. The registrar sold you the name. The registry manages the top-level domain, so Nominet UK for anything ending in .uk. The authoritative nameservers publish your records, and that’s the part you control.
Your nameservers are set at the registrar and they point at whoever hosts your zone. Where a domain uses our nameservers, the records live in your hosting control panel, and the KB walks through managing your nameservers and editing your DNS zone. Registering through us puts the name and the zone behind one login, which is the practical argument for buying domain names from the company already running the server.
What breaks when a record is wrong
DNS faults break along clean lines, so the symptom usually tells you which record to open. A website that fails to load anywhere points at the A record or at the nameservers. Email that sends fine and never arrives points at the MX records. Messages that arrive and land in junk point at SPF or DMARC.
People often overlook certificates. To issue an SSL certificate, the name must resolve to the server making the request. If an A record still points to an old host, it will block the certificate long before anyone notices the missing padlock.
How long a change takes to apply
Each record has a time to live, which is a number of seconds telling resolvers how long they can keep the answer before asking again. The DNS specification, RFC 1035, defines it exactly that way, and it accounts for the whole of what people call propagation. Nothing goes out across the internet when you save a record. Old copies expire on their own clock.
It helps to drop the TTL on a record a day before you plan to change it, then raise it again once the new value is live. If you’re waiting on a change now, our KB covers checking DNS propagation and flushing the resolver cache on your own machine, which is often all that stands between you and the new answer.
DNS is a small amount of text doing a large amount of work, and it feels obscure because most people meet it once every few years under pressure. Learn which record answers which symptom and the rest becomes routine maintenance. Export a copy of the zone before you touch anything.
Check who controls the nameservers for your domain before your next renewal, and see if you can access the zone directly. If it’s a bit of a faff, shift the registration while things are still running smoothly. The domain names page is the place to start.
