You can add a CNAME (alias) record to your DNS (Domain Name System) zone file for a domain registered.
Below are few Guides to add Cname on different DNS providers :
- Basic - https://support.google.com/a/answer/47283?hl=en
- GoDaddy https://sg.godaddy.com/help/add-a-cname-record-19236
- NameCheap: https://www.namecheap.com/support/knowledgebase/article.aspx/9646/2237/how-to-create-a-cname-record-for-your-domain