why does connect domain to “Shopify” ask for either CNAME and A Record?

问题

why does connect domain to "Shopify" ask for either CNAME and ARecord? ref

If you've purchased your domain through a third party, then you need to edit the following DNS settings:

Your A record should point to Shopify's IP address, which is 23.227.38.65 Copy

Your www CNAME record should point to shops.myshopify.com Copy .

I mean if i configure my domain customer.com, A Record => 23.227.38.65

Isn't that enough to them? why do they also ask for CNAME www shops.myshopify.com?

来源：https://stackoverflow.com/questions/61544603/why-does-connect-domain-to-shopify-ask-for-either-cname-and-a-record