If the public address resembles `portalname.zohodesk.com/portal` or the older `desk.zoho.com/portal/` format, it is a Zoho Desk default address. If it resembles `support.mycompany.com`, it is a branded custom subdomain and should be managed through domain mapping.
For example, `zylker.zohodesk.com/portal` is a default Zoho Desk address, while `support.zylker.com` is a mapped custom domain.