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A domain (sometimes called a domain name) is a user-friendly address used to access websites on the internet. It serves as a readable representation of an IP address, which is the numerical identifier computers use to locate each other on the network.

Adding a domain that you own to Fastly ensures that others cannot serve requests to your domain. Additionally, by routing your domain's traffic through Fastly, you can store cached copies of important information as close to your users as possible, helping to speed up its delivery to them.

To use your domain with Fastly:

1. Add the domain name that visitors use to access your website or application to a Fastly service. Fastly treats all fully qualified domain names (FQDN) as a domain, whether it's an apex domain like example.com or subdomain like www.example.com or *.example.com. When possible, use a subdomain instead of an apex domain for more resilient, faster routing.
2. Secure your domain by configuring Fastly TLS to serve secure traffic using HTTPS. Fastly requires a TLS certificate as proof of ownership of the domain. You can use Fastly's managed TLS to get a certificate or bring your own valid TLS certificate to prove ownership.
3. Test everything to make sure things are working the way you expect.
4. Update your DNS records to route production traffic for your domain through Fastly.

Adding a domain to Fastly

There are two types of domains that can be added in Fastly: versionless domains and classic domains.

Working with versionless domains

Click Domains from the navigation sidebar to access the Domain management page. The Domain management page lets you add a domain, procure a Fastly-managed TLS certificate, and associate a domain to a service, all at the same time. These domains are versionless, which means they aren't tied to a specific service version. This lets you add your domain to Fastly even if you're not ready to link it to a service and make changes to the domain without having to increment a service version. There is also no limit to the number of domains you can add to your service.

Delegating versionless domains to other accounts

The Domain management page provides a self-service mechanism for performing domain delegation. For example, you may want to delegate a domain to another account (such as when you need to delegate a domain from a test account to a production account) or even another customer. A domain can be delegated by proving domain ownership through one of the following:

• having Fastly procure a Fastly-managed certificate via a DNS challenge for you, and then setting a token in your DNS settings
• providing Fastly a valid TLS certificate (and matching key) from a publicly-trusted certificate authority

Working with classic domains

Classic domains are created within, and therefore associated with, a specific service and service version. To make any changes to the relationship between domain and service, you must create a new version of the service.

When creating classic domains, we set a limit on the number of domains you can create per service by default based on your account type and any packaged offering you've purchased. Once you reach that limit, error messages may appear that look something like this:

{
  "msg": "An error occurred while connecting to the fastly API, please try your request again.",
  "detail": "Exceeding max number of domains: 10"
}

If you're receiving a limit message and need to create more services or domains, contact support for assistance. Fastly support engineers can increase the number of services that you can use and suggest other ways to design what you are trying to achieve.

Delegating classic domains to other accounts

Classic domains can only be associated with one service at a time. If a domain is in use by another service within your account, you can delete the domain and add it to the other service. However, if a domain is used by a service in another Fastly account, it can't be used without being delegated.

If you try to create a domain that is already owned by another customer, you may get error messages like:

• Domain [domain name] is taken by another customer.
• Domain [domain name] is owned by another customer.

If you receive one of these errors when adding a domain that you rightfully should have access to, or if you need to delegate a domain to another account or customer (for example, when you need to delegate a domain from a test account to a production account), contact support to help you delegate the domain to the correct account.

Securing domains with TLS

TLS is used to form secure server connections so traffic can be served over HTTPS. When creating a versionless domain using Domain management, you can have Fastly automatically procure a Fastly-managed TLS certificate using Certainly at the time of domain creation.

If you don't automatically procure a TLS certificate when working with Domain management or are using classic domain, you can set up a Fastly-managed TLS certificate or bring your own TLS certificate when you're ready.

Testing domains

Fastly won't begin serving traffic for your domain until you update your DNS records and activate your service. Before doing this, you can check to see how your service is pulled through our network and identify any DNS issues or problems with your Fastly configuration.

Updating DNS records to point to Fastly

Once you're ready to have Fastly serve production traffic for your domain, you'll need to update your DNS records to point to Fastly by setting up a CNAME record for the domain.

What's next

Once you understand how domains work and their limits, add a domain to Fastly.

Related content

• Domains and origins
• Routing traffic to Fastly
• Domain API documentation