Domains and DNS

In this chapter, we’ll talk about domains within the larger context of the Domain Name System, or DNS. While this is a more technical chapter, we hope to be able to explain it in a way that helps you feel confident when tackling any DNS-related setup work.

In very basic terms, the resources for a website (like its code and images) are stored on a server connected to the internet. These servers, as well as home computers and other devices connected to the internet, are identified by IP addresses. An individual IP address is made up of four sets of numbers (for example, 172.217.8.206).

To make it easier for both humans and machines (like search engines) to find and use websites, a domain name is used as an “alias” in place of the actual IP address, which is harder to remember and type.

As an example, google.com is an alias of the IP address 172.217.12.78. Try typing that IP address directly into your address bar, and it should resolve to Google. However, most people find it easier to remember google.com than an IP address.

The system used to translate IP addresses and domain names is called the Domain Name System (DNS). DNS handles the names and addresses for all computers, services, and other resources on the internet.

So how does this translation occur? DNS uses different type of records to designate where individual services should be hosted. The record type used depends on which resource is being hosted (web versus email) and how you want to direct it (the whole domain or a subdomain; by IP or by name).

The most primary DNS records are called nameservers, which determine who the default host of your DNS is. All hosting resides with the nameserver host unless it is specified by that host to point elsewhere.

For example, when you purchase a domain from a registrar, that registrar starts as your nameserver host. Therefore, any DNS records have to be set up at that host. From the registrar’s control panel, you may point your nameserver records to BigCommerce, which would then make BigCommerce your DNS host. Any new records would need to be set up from BigCommerce.

Below, we’ll talk about the different types of DNS records and when they’re used.

The primary DNS records are listed in the table below:

A Records

An A record translates a human-friendly domain name into an IP address and is the most commonly used record. The A record for your BigCommerce store is configured automatically, and most stores will never need to change it.

MX Records

MX records specify the email servers to be used for a domain. These point to another domain name rather than an IP address, like “mail.service.net”. BigCommerce does not offer email hosting; you’ll need to collect MX records from your email hosting provider and configure them in your BigCommerce store’s DNS settings. See Third-Party Email Hosting for guidance.

CNAME Records

A CNAME record is used to set up subdomains for your domain. A common CNAME record, and one already configured for your BigCommerce store, is for the “www” subdomain. A CNAME record tells a visiting computer that “www.mybcstore.com” is an alias of “mybcstore.com”. This makes it so if a shopper visits the www URL, they are shown the non-www site. Your mail host may also require setting up CNAME records along with MX records.

If your domain is hosted on another site, and you’d like to have a subdomain of that domain point to your BigCommerce store, you’d create a CNAME record to point a “shop.” or “store.” subdomain to your BigCommerce store’s permanent address.

TXT Records

A TXT record does not direct traffic per se, but allows a way to provide human-readable text information via DNS records. In addition, a common TXT record is used for email in the form of a Sender Policy Framework (SPF). Basically, this kind of TXT record prevents spammers and other unauthorized entities from sending messages from your domain name by specifying exactly who has permission to send mail on behalf of that domain.

A TXT record that includes BigCommerce.com as an allowed sender is usually necessary in order for the store to send email from the domain.

When referring to DNS, propagation refers to the time it takes for a particular DNS change or update to take effect across the entire world. While the internet allows for communication at essentially the speed of light, DNS remains a decentralized system, so interconnected servers and other infrastructure may check for and apply DNS updates at different times and intervals.

For this reason, DNS changes take time, sometimes up to 72 hours. Before a change has completely propagated, some internet users may be accessing the new, updated address information while others are still configured to use the old address information.

When the nameservers are changed for a domain, it can take anywhere from 24 - 72 hours before the domain is “fully propagated”, meaning internet infrastructure around the world has been updated with the new data. In addition, a site may only be intermittently available in certain areas until propagation completes.

During this time, it’s possible for a visitor on one side of the world to access the domain from the old host (old nameservers), while visitors on the other side of the world are getting the domain from the new host (updated nameservers). For a newly purchased domain, it’s typical for the old host or default nameservers to route the domain to a standard “domain parking spot” or “future home of” type landing page.

Once the nameservers for a domain have fully propagated, changes to other DNS records for host-controlled domain records (like A, MX, and CNAME records) typically take affect much faster — usually within a couple of minutes.

There are several online tools to help you track propagation after a nameserver change, like whatsmydns.net. These tools can help you to visualize which geographies/regions your nameserver changes have been picked up by, and which are still awaiting the update.

While being versed in the technical specifics of how the web works isn’t necessary to running an online business, it’s good to have a general understanding of basic internet concepts so you are better prepared for the questions or challenges you may encounter on your ecommerce journey.

If you’d like to learn more about the history and technical side of domains and DNS, WebHostingGeeks has a great DNS guide. Websites like Wikipedia and HowStuffWorks are also good resources for information on DNS.

For more information on managing your DNS in BigCommerce, see the following resources:

• Finding Your Web Address
• Changing Domains
• Purchasing a Domain
• Managing DNS
• Email in BigCommerce
• Third-Party Email Hosting
• Troubleshooting DNS