DNS records are the instructions that tell the internet where your website and email live. An A record points your domain to your web server, a CNAME points one name at another name, and an MX record tells other mail servers where to deliver your email. Get one wrong and your site or inbox goes quiet, even though nothing else has changed.
Key takeaways
- Your website is usually controlled by A records (or a CNAME on the www name). Your email is controlled by MX records.
- TXT records prove you own the domain and tell inboxes which servers may send your email.
- A name with a CNAME can’t hold any other record, which is why the bare domain usually uses an A record.
- Most DNS outages come from a change made in the wrong place, or an old record left behind.
- Before you change anything, save a copy of every record so you can put it back.
What is DNS, in plain English?
DNS (the Domain Name System) is the internet’s address book. People remember names like yourbusiness.com.au. Computers need numbers, called IP addresses. DNS translates one into the other, every time someone visits your site or sends you an email.
Your domain’s DNS lives in a “zone”: a short list of records held by whichever company runs your DNS. That might be your registrar, your host or a service like Cloudflare. Which company is in charge depends on your nameservers. If you’re not sure where to make a change, start with our guide to nameservers vs DNS.
Every record has the same basic parts: a name (such as www), a type (such as A or MX), a value (where it points) and a TTL, which says how long other computers may remember the answer.
What does each DNS record do?
Most small business zones only use six or seven record types. Here’s what each one does, and what you’ll notice if it’s wrong.
A and AAAA records: where your website lives
An A record maps a name to an IPv4 address, such as 203.0.113.10. An AAAA record does the same for the newer, longer IPv6 addresses (Cloudflare). Your bare domain (yourbusiness.com.au, often shown as @) almost always uses an A record.
When you move hosts, the A record is the one that changes. A common slip is updating it and forgetting an old AAAA record that still points at the previous server. Visitors on IPv6 then see the old site, or nothing at all.
CNAME records: one name pointing at another
A CNAME says “this name is really that name”. For example, www.yourbusiness.com.au might point to yourbusiness.com.au, or shop.yourbusiness.com.au might point to a platform’s address. If the target’s IP address changes, the CNAME follows it automatically.
There’s one strict rule. The DNS standard says that if a CNAME is present on a name, “no other data should be present” (RFC 1034). Your bare domain must also hold MX and NS records, so it can’t normally be a CNAME. Some DNS providers work around this. Cloudflare’s “CNAME flattening” looks up the target and answers with its IP address instead (Cloudflare).
CNAMEs are also how most subdomains get connected to outside services, such as a booking system or an online store.
MX records: where your email goes
MX (mail exchange) records tell other mail servers where to deliver email for your domain. Each one has a priority number. Lower numbers are tried first: the email standard says records with the “lowest-numbered records being most preferred” (RFC 5321).
When you change email provider, remove the old MX records. Google Workspace, for example, uses a single MX record (smtp.google.com, priority 1) and warns that “your email might not work correctly if you keep old or incorrect MX records” (Google Workspace Admin Help).
TXT records: proof and email rules
TXT records hold short pieces of text. Services like Google and Microsoft ask you to add one to prove you own the domain. TXT records also carry SPF and DMARC, which tell inboxes which servers may send email as you. Our SPF, DKIM and DMARC guide covers those in detail.
The classic mistake is adding a second SPF record when you sign up for a new email tool. The SPF standard says a domain “MUST NOT have multiple records” of this kind (RFC 7208). Two SPF records means both fail. Merge them into one instead.
NS records: who’s in charge
NS records name the servers that answer for your domain. They’re set at your registrar. Change them and you hand the whole zone to a different company, so every record must already exist there first. This is the most powerful setting in your domain account, and the easiest way to take a site and email offline in one click.
CAA records: who can issue your SSL certificate
A CAA record lists the certificate authorities allowed to issue SSL certificates for your domain. With no CAA record, any public authority can issue one once it validates you control the domain (Let’s Encrypt). CAA records are optional. If you add one, make sure it includes the authority your host uses, or your free certificate won’t renew.
What breaks when a DNS record is wrong?
DNS problems tend to look like something else. This table matches common symptoms to the record that usually causes them.
| What you notice | Record to check first |
|---|---|
| Website doesn’t load, but email works | A record on @ and www |
| yourbusiness.com.au works but www doesn’t | CNAME or A record on www |
| Some people see the old site after a move | Old A or AAAA record, or a long TTL |
| Email stopped arriving after a change | MX records |
| Your emails land in customers’ spam | SPF and DMARC TXT records |
| Website and email both died at once | NS records, or an expired domain |
| SSL certificate won’t renew | A record or CAA record |
In our experience, the cause is rarely a fault at the DNS provider. It’s usually a record edited in one account while the domain’s nameservers point to another, or an old record nobody removed.
Why don’t DNS changes work straight away?
Every record has a TTL (time to live), measured in seconds. Computers around the world cache your answer for that long. If your A record has a TTL of 14,400, some visitors may keep reaching the old server for up to four hours after you change it. Our article on DNS propagation explains the wait and how to shorten it before a planned change.
How do I check my DNS records?
Log in to whichever company your nameservers point to and look at the zone. To see what the rest of the internet sees, use a public lookup such as Google’s free Admin Toolbox Dig. Type in your domain and it shows the live records.
DNS records are public by design. Anyone can look up your MX or A records. That’s separate from the owner details shown in WHOIS, which our guide to domain privacy in Australia explains.
How do I change DNS records safely?
- Find where DNS is hosted. Check your nameservers first. Editing a zone that isn’t live changes nothing.
- Save a copy of every record. Export the zone or take screenshots, including TXT values. This is your undo button.
- Lower the TTL a day ahead. Drop it to 300 seconds (five minutes) on the records you plan to change, so a mistake clears quickly.
- Change one thing at a time. Update the A record for the website, then test. Change MX records separately, then test email.
- Remove what’s no longer used. Old AAAA, MX and SPF records cause most of the “it half works” problems.
- Test from outside. Check the live records with a public lookup, load the site on mobile data, and send a test email from an outside account.
Moving hosts is when most DNS mistakes happen, because the website, email and SSL all change at once. If you’re planning a move, read how our free website migration works before you touch a record.
Should my registrar, host or a third party run my DNS?
Any of them can work. What matters is that you know which one is live, you can log in to it, and one person owns changes. Keeping the domain, DNS and hosting with one provider means fewer logins and fewer places for a record to hide. Our domain and DNS management service is built for exactly that. If you’re starting fresh, you can register your domain with WMS and keep everything together from day one.
Frequently asked questions
What is the difference between an A record and a CNAME?
An A record points a name straight to an IP address. A CNAME points a name to another name, which then resolves to an address. Use an A record for your bare domain and a CNAME for subdomains that point to outside services.
Will changing my A record affect my email?
Not on its own. Email follows the MX records, not the A record. But if your MX record points to a name like mail.yourbusiness.com.au, and that name’s A record points to your old host, email can break when the old hosting is cancelled.
Can I have two MX records?
Yes, if they belong to the same email provider. Many providers use several MX records with different priorities as backups. Mixing records from two different providers splits your email between them, so remove the old provider’s records when you switch.
What TTL should I use?
An hour or more is fine for records that rarely change. Lower it to five minutes a day before a planned change, then raise it again once everything works. A short TTL all the time is harmless but adds a little lookup work.
Do I need to touch DNS if I only change my website design?
No. A redesign on the same hosting doesn’t change any records. DNS only needs updating when the site or email moves to a different server or provider, or when you add a new service that asks you to verify the domain.
Sources
- DNS record types, Cloudflare Docs
- RFC 1034: Domain names, concepts and facilities, section 3.6.2, IETF, 1987
- CNAME flattening, Cloudflare Docs
- RFC 5321: Simple Mail Transfer Protocol, section 5.1, IETF, 2008
- Set up MX records for Google Workspace, Google Workspace Admin Help
- RFC 7208: Sender Policy Framework, section 3.2, IETF, 2014
- Certificate Authority Authorization (CAA), Let’s Encrypt
- Dig, Google Admin Toolbox