DNS Records Explained: What Are A Records, B Records and CNAME Records in DNS?

If you have ever set up a website, migrated a domain, or troubleshot an email delivery problem, you have almost certainly come across DNS records. For many people, the world of DNS (Domain Name System) feels like a confusing maze of technical jargon. However, once you understand the basics, it becomes far more manageable. In this guide, we will break down DNS records explained in plain English, covering A records, B records, and CNAME records, so you can confidently manage your domain settings without scratching your head.

What Is DNS and Why Does It Matter?

Before diving into specific record types, it helps to understand what DNS actually is. The Domain Name System is essentially the internet’s address book. When you type a web address such as example.co.uk into your browser, your computer does not inherently know where to find that website. DNS translates that human-readable domain name into an IP address — a numerical label that computers use to identify each other on a network.

Without DNS, you would need to memorise a string of numbers every time you wanted to visit a website. DNS records are the individual entries within this system that tell the internet where to route traffic, where to deliver emails, and how to handle various types of requests associated with your domain.

Managing DNS records correctly is critical for website performance, email deliverability, and overall online presence. A misconfigured DNS record can take your website offline or cause emails to bounce, so understanding each record type is genuinely important.

What Is an A Record?

The A record is arguably the most fundamental DNS record type you will encounter. The “A” stands for “Address,” and its job is straightforward: it maps a domain name to an IPv4 address.

How Does an A Record Work?

When someone types your domain name into their browser, the DNS system looks up your A record to find the IP address of the server where your website is hosted. For example, if your domain is mybusiness.co.uk and your hosting server has an IP address of 185.100.20.50, your A record would point your domain to that specific IP address.

You can also create A records for subdomains. For instance, you might have a separate A record pointing shop.mybusiness.co.uk to a different server that hosts your e-commerce platform. This flexibility makes A records incredibly useful for businesses running multiple services under the same domain.

Key Facts About A Records

• They only work with IPv4 addresses (four sets of numbers separated by dots).
• For IPv6 addresses, you would use an AAAA record instead.
• Every domain that hosts a website needs at least one A record.
• Multiple A records can be created for the same domain to enable load balancing.

What Is a B Record?

Here is where many people get confused — because in standard DNS terminology, there is no official “B record.” The DNS system does not include a record type formally designated as a B record in the way that A records or CNAME records exist.

Where Does the Term “B Record” Come From?

The term “B record” is sometimes used informally or mistakenly by people who are new to DNS management. It may arise from confusion with other record types, or it could be a misremembering of the naming convention. In some proprietary systems or specific software platforms, the term may be used internally, but it is not part of the standard DNS specification as defined by the Internet Engineering Task Force (IETF).

If you have come across the term “B record” in documentation or a tutorial, it is worth double-checking the source. It is possible the author was referring to another record type entirely, such as an MX record (for email routing), a TXT record (for domain verification and security), or even an AAAA record for IPv6 addressing.

What Should You Use Instead?

If you are trying to achieve a specific DNS function and someone has told you to create a “B record,” clarify exactly what they mean. The most common DNS record types you are likely to need include A records, AAAA records, CNAME records, MX records, TXT records, NS records, and SOA records. Each serves a distinct purpose, and understanding which one you need is far more useful than chasing a record type that does not officially exist.

What Is a CNAME Record?

CNAME stands for Canonical Name. Rather than pointing a domain to an IP address like an A record does, a CNAME record points one domain name to another domain name. This makes it particularly useful for subdomains and aliasing.

How Does a CNAME Record Work?

Imagine you want www.mybusiness.co.uk to behave exactly like mybusiness.co.uk. Instead of duplicating the A record, you can create a CNAME record that points www.mybusiness.co.uk to mybusiness.co.uk. The DNS system then follows the chain: it looks up www.mybusiness.co.uk, finds the CNAME pointing to mybusiness.co.uk, and then looks up the A record for mybusiness.co.uk to find the actual IP address.

CNAME records are also widely used when integrating third-party services. For example, if you use a marketing platform or a customer support tool that requires you to host it on a subdomain like help.mybusiness.co.uk, the provider will often ask you to create a CNAME record pointing that subdomain to their own domain. This allows them to serve content from their servers whilst keeping your branding intact.

Important Limitations of CNAME Records

• You cannot create a CNAME record for a root domain (also called an apex domain). For example, you cannot set a CNAME for mybusiness.co.uk itself — only for subdomains.
• A CNAME record cannot coexist with other record types for the same name. If a subdomain has a CNAME, it cannot also have an MX or TXT record.
• CNAME records can add a small amount of latency because of the extra lookup step, though in practice this is rarely noticeable.

How Do These Records Fit Together?

Understanding DNS records explained individually is helpful, but seeing how they work together gives you a much clearer picture. A typical domain setup might include an A record pointing the root domain to a hosting server, a CNAME record pointing the www subdomain to the root domain, MX records directing email to a mail provider, and TXT records verifying ownership with Google or Microsoft.

Getting these records right ensures your website loads correctly, your emails are delivered reliably, and your domain functions as intended. For a deeper dive into domain management best practices, take a look at the resources available at da-manager.com/blog, where you will find practical guidance on keeping your online presence in top shape.

Tips for Managing DNS Records Effectively

Always Double-Check Before Making Changes

DNS changes can take anywhere from a few minutes to 48 hours to propagate across the internet, depending on the TTL (Time to Live) settings on your records. Making a mistake can cause downtime, so always verify your entries before saving them.

Keep a Record of Your DNS Settings

Before making any changes, take a screenshot or export your current DNS settings. This gives you a reference point if something goes wrong and you need to revert to the previous configuration.

Use Low TTL Values When Testing

If you are experimenting with new DNS settings, temporarily reduce the TTL value so that changes propagate more quickly. Once you are confident everything is working correctly, you can increase the TTL again to improve performance.

Final Thoughts

DNS records explained simply come down to this: they are the instructions that tell the internet how to handle requests for your domain. A records point your domain to an IP address, CNAME records create aliases between domain names, and whilst B records are not an official DNS record type, understanding this helps you avoid confusion when reading documentation or following technical guides.

Whether you are launching a new website, switching hosting providers, or integrating a third-party service, a solid grasp of DNS records will save you time, frustration, and potential downtime. Take the time to understand your DNS settings, and your online presence will be all the stronger for it.