Type a web address, and before anything loads, your computer asks a question: where is this? The answer comes from DNS, the domain name system. It is the phone book of the internet, and your business has an entry in it.

Most owners never look at their entry. That is fine until the day email stops or the website vanishes, and the fix turns out to be one line in a place nobody remembers the login for. Here is what is in there, in plain English.

Nameservers: who holds the book

Your domain is registered somewhere. Separately, somebody hosts its DNS records. The nameserver setting at the registrar says who. It might be the registrar, your web host, or a service like Cloudflare.

This is the first thing to know, because every other change happens wherever the nameservers point. If the nameservers point at a host you stopped paying years ago, you cannot change anything, and one day the records disappear.

A record: where the website lives

The A record maps a name to an address. yourcompany.com points at the server that holds your site. Change hosts and this is the line that moves.

CNAME: a nickname

A CNAME says one name is really another. www.yourcompany.com is usually a CNAME for yourcompany.com. Services you sign up for often ask for one: a CNAME that points shop.yourcompany.com at their platform, for example.

MX: where the email goes

MX records say which servers receive mail for your domain. Google Workspace and Microsoft 365 each give you a set. Get these wrong and mail bounces or, worse, silently goes to an old provider. When a business moves email platforms, the MX change is the actual moment of the move.

TXT: the notes in the margin

TXT records hold text that other systems read. The three that matter most are the email ones: SPF, which lists who may send as you; DKIM, the signature key; and DMARC, the rule for what to do when a message fails. Verification codes from Google, Microsoft and others also live here. Over the years a domain collects a pile of them. Most are harmless. Some are from tools you no longer use.

Three mistakes we see every month

The forgotten subdomain. An old shop.yourcompany.com or dev.yourcompany.com still points at a platform you cancelled. Anyone who signs up for that platform can claim the name and put their content under your domain. The fix is to delete records for things you no longer run.

The lapsed host. Nameservers at a company nobody pays. The records work until they do not. Move DNS somewhere you control and pay for.

The guess. Someone changes a record to fix one thing and breaks another, usually mail, because SPF was edited in a hurry. Every DNS change should be written down: what changed, who changed it and why.

Who should hold the login

Two people at the company should be able to reach the DNS account, with two-step sign-in on it, and neither of them should be a vendor. A vendor can be the technical contact and make changes on request. The account itself, like the domain, belongs to the business. When an agency or a former employee holds it, you are one unanswered email away from a website you cannot change.

How to look at yours

Any lookup tool will show your records. Search for a DNS lookup, type your domain, and look at each type above. Check the nameservers first, then the MX, then the TXT records. Ask of each line: do I know what this is for? If the answer is no, find out before you delete it.

What ALCO does

For the domains we manage, the domain stays in your company's name with ALCO as the technical contact. DNS is hosted on Cloudflare and changed through the help desk, with a record of who changed what. Email records are set and checked. Certificates renew on their own. Stray subdomains are found and removed. If your domain is sitting in an ex-employee's or an old agency's account, we help you get it back; we have done it before.

The full list is at https://alcohq.com/services/domains-and-dns

A domain is a small thing to look after and a large thing to lose. Ten minutes with the records now saves a bad week later.