A subdomain is a more specific part of that domain that can be assigned to a particular part of your site, for example, blog.acme.com, help.acme.com. This helps to blend both your brand, with the specificity of where the user may need to go. To add a subdomain to your Project, follow the instructions in the Add a custom domain doc. If you have bought the domain through Vercel, you can also point a subdomain to an external service through the Domains section of the dashboard. Subdomains are set through a CNAME DNS record.
Adding a CNAME record
Locate the value and the name arguments requested by the external provider and use them in the DNS UI, replacing name with the name provided, and cname.vercel-dns.com with the value:
Using Cloudflare as Your DNS Provider
To use Cloudflare as your DNS provider, follow the steps below:
Insert a DNS Record
In your Cloudflare dashboard, create a CNAME record pointing your domain to cname.vercel-dns.com.
Disable the Cloudflare Proxy
Set the Proxy status to DNS only. This ensures DNS queries result in Vercel serving the request instead of Cloudflare.