DNS is the part of your website nobody thinks about until it breaks, and then it tends to break everything at once: the site, the email, or both. It has a reputation for being arcane, and it does hide some genuinely fiddly corners. But the list of records a small business actually needs is short, and knowing what each one is for takes most of the fear out of it.
The records that point people at your site
The one that matters most is the A record. It maps your domain to the IPv4 address of the server your site lives on, so that typing your name into a browser finds the right machine. AAAA does the same job for IPv6 addresses: it’s a separate record type for a different kind of address, not a replacement for the A record, so if you have both, they sit side by side.
The other everyday one is the CNAME, which points one name at another. It is how “www” and any subdomains ride along without you writing the address out in several places. Get these wrong and the site is unreachable, which is exactly why they’re the first thing we look at when a site “vanishes” the morning after a move.
The records that carry your email
Email runs on a completely separate set of records, and this is where small businesses lose the most ground. MX records name the servers that receive mail for your domain. That part most people manage to get right, because without it no mail arrives at all and the problem is obvious.
The harder part is the three TXT records that decide whether the mail you send is believed. SPF lists who is allowed to send as you. DKIM signs your messages so they can’t be quietly forged. DMARC tells the receiving side what to do when a message fails the first two. Skip them and your own invoices start landing in spam folders.
The sprawl worth resisting
Beyond the records above, the useful advice is mostly restraint. Every service you sign up for wants to add its own verification record, and it’s easy to end up with a DNS zone full of entries nobody can account for. Old records left behind after you stop using a service are their own small security risk. A short, current set of records is far easier to reason about than a long one nobody has read in years.
One setting is worth knowing before you start pruning: TTL, which is how long the rest of the internet is allowed to remember a record before checking again. Turn it down a day before a planned move so the change takes effect quickly, and leave it at a normal value the rest of the time.
Get it right once
DNS rewards being boring. Once the handful of records above are correct, they mostly sit there and work, and the failures we see almost always come from a change made in a hurry by someone who didn’t know what a record was for. That is the case for keeping DNS with the people who host and look after the site: the records, the site, and the email stay one picture, changed on purpose and checked afterwards. It’s also how you avoid the version of this we see go wrong most often, which is good email landing in spam because the sending records were never set up at all.