You have business and you want promote to your business on internet then you need a unique internet name mean DOMAIN name .
DOMAIN : Domain a unique name for your website . Choose a unique domain as per your business name. For domain register need a domain registrar site for domain registration you can visit shop.sakhihosting.in .
If you registered domain with hosting then no need any change of DNS setting its automatic setted by domain registrar ( if domain registrar provided hosting service ).
If you register a domain without hosting service then need DNS setted by you as per your server . eg . ns1.yourservername ,ns2.yourservername .For any website domain must be set minimum 2 DNS.