If you are hosting your website on HubSpot CMS you will normally need to redirect your root domain (domain.com) to your www subdomain (www.domain.com). As of Jan 2021, HubSpot CMS Enterprise can host content on the root domain.
There are two common ways to redirect your root domain to your www subdomain:
1. If you'll be hosting your entire website with HubSpot and your DNS provider supports forwarding, set up a redirect in your DNS settings so your non-www domain (such as domain.com) will forward to your www domain (such as www.domain.com).
2. If your DNS provider doesn't support forwarding, you need to set up a basic website hosting and point the A record of your root domain(domain.com) to the IP Address of your web host and set up the redirect in CPanel or via the hidden htaccess file.
Here are some HubSpot articles that may help you understand the technical requirements and how you can fully go-live with HubSpot: