DNS Records Explained: MX, A, and CNAME Records for Small Businesses

If you've ever set up a website or configured email for your business, you've probably encountered DNS records. These cryptic abbreviations—MX, A, CNAME—can seem intimidating at first, but they're actually straightforward once you understand what each one does.

Think of DNS (Domain Name System) as the internet's phone book. When someone types your domain name into a browser, DNS records tell the internet where to find your website, where to send your email, and how to connect various services to your domain. Let's break down the three most common types you'll work with.

What Are A Records?

An A record (Address record) is the most fundamental DNS record type. It points your domain name directly to an IP address—the numerical address where your website lives on the internet.

When someone types "yourcompany.com" into their browser, the A record tells their computer: "Go to this specific IP address to find that website." For example, your A record might point yourcompany.com to something like 192.0.2.1.

Common uses for A records:

• Pointing your main domain (yourcompany.com) to your web server
• Directing subdomains (blog.yourcompany.com) to specific servers
• Setting up multiple websites on different servers under the same domain

Most small businesses need at least one A record for their primary domain. If you're working with a web hosting provider or website developer, they'll typically provide you with the IP address you need to use in your A record.

Important note: A records only work with IPv4 addresses (the standard format like 192.0.2.1). If you need to use an IPv6 address (the newer, longer format), you'll use an AAAA record instead, which works the same way.

What Are CNAME Records?

CNAME stands for Canonical Name, but it's easier to think of it as an alias. Instead of pointing to an IP address like an A record does, a CNAME points one domain name to another domain name.

Let's say you want "www.yourcompany.com" and "yourcompany.com" to go to the same place. You could create two separate A records, but that means updating both if your IP address ever changes. Instead, you can create one A record for yourcompany.com and a CNAME record that points www.yourcompany.com to yourcompany.com. Now you only need to update one record if things change.

Common uses for CNAME records:

• Pointing www.yourcompany.com to yourcompany.com
• Connecting third-party services (like email marketing platforms) to custom subdomains
• Setting up subdomains that redirect to external services (shop.yourcompany.com pointing to your Shopify store)
• Verifying domain ownership for various services

Key limitation: You cannot create a CNAME record for your root domain (yourcompany.com). CNAME records only work for subdomains (www.yourcompany.com, blog.yourcompany.com, etc.). This is a technical requirement of how DNS works.

What Are MX Records?

MX records (Mail Exchange records) tell the internet where to deliver email for your domain. When someone sends an email to you@yourcompany.com, their email server looks up your MX records to find out which mail server should receive that message.

Unlike A records, MX records include a priority number. This lets you set up backup mail servers in case your primary server is down. Lower numbers mean higher priority, so an MX record with priority 10 will be tried before one with priority 20.

Common uses for MX records:

• Directing email to Google Workspace (formerly G Suite)
• Routing email to Microsoft 365
• Pointing to your web host's email servers
• Setting up backup mail servers for reliability

Most small businesses use email services from providers like Google or Microsoft, and these providers give you specific MX records to add to your domain. You might have multiple MX records with different priorities to ensure email delivery even if one server has issues.

Example MX record setup for Google Workspace:

• Priority 1: ASPMX.L.GOOGLE.COM
• Priority 5: ALT1.ASPMX.L.GOOGLE.COM
• Priority 5: ALT2.ASPMX.L.GOOGLE.COM

The lower priority number (1) is tried first, with the others serving as backups.

How These Records Work Together

In a typical small business setup, you'll use all three record types:

1. A record points yourcompany.com to your web server's IP address
2. CNAME record points www.yourcompany.com to yourcompany.com
3. MX records point your email to Google Workspace or Microsoft 365

You might also have additional CNAME records for specific services. For example, if you use a third-party email marketing tool, they might ask you to create a CNAME record like "email.yourcompany.com" pointing to their servers.

Making Changes to DNS Records

You manage DNS records through your domain registrar (where you bought your domain) or through your DNS hosting provider. The interface varies, but the basic process is similar:

1. Log into your domain management panel
2. Find the DNS settings or DNS zone editor
3. Add, edit, or delete records as needed
4. Save your changes

One important thing to know: DNS changes aren't instant. Due to caching across the internet, changes can take anywhere from a few minutes to 48 hours to fully propagate. In practice, most changes are visible within a few hours.

Pro tip: Before making changes to existing records, write down or screenshot your current settings. This makes it easy to revert if something goes wrong.

Common Mistakes to Avoid

Don't delete records you don't recognize. If you see DNS records you didn't create, they might be there for email authentication (SPF, DKIM, DMARC) or service verification. Research them before removing.

Don't use CNAME for your root domain. As mentioned earlier, CNAME records don't work for yourcompany.com—only for subdomains like www.yourcompany.com.

Don't forget the trailing dot. Some DNS interfaces require a period at the end of domain names in records (like "mail.google.com."). Check your provider's documentation.

Don't mix A and CNAME records for the same subdomain. You can have either an A record or a CNAME record for www.yourcompany.com, but not both.

When to Get Help

DNS configuration is powerful, and mistakes can take your website or email offline. If you're not confident making changes yourself, it's worth getting help. A misconfigured MX record means lost email. A wrong A record means a down website.

If you need assistance with website setup or DNS configuration, our team can help ensure everything is configured correctly the first time. Contact us to discuss your specific needs.

FAQ

How long do DNS changes take to go into effect?

DNS changes typically propagate within 1-4 hours, though the official maximum is 48 hours. The time depends on TTL (Time To Live) settings and how various servers cache DNS information. If you're planning changes, it's best to do them during low-traffic periods and allow 24 hours for full propagation.

Can I have multiple A records for the same domain?

Yes, you can have multiple A records pointing to different IP addresses. This is called round-robin DNS and can be used for basic load balancing. However, for most small businesses, a single A record is sufficient. Multiple A records are more common for high-traffic sites or redundancy setups.

What happens if I delete my MX records?

If you delete your MX records, email sent to your domain will bounce back to senders. The sending mail servers won't know where to deliver the messages. If you accidentally delete your MX records, restore them as quickly as possible. Email sent during the time they were missing will typically bounce and won't be delivered once you restore the records.