Every registered domain name has no less than 2 Name Server records which show where it's hosted i.e. by using these records you direct your domain name to the servers of a specific hosting provider. In this way, you have got both your website and your e-mails managed by the exact same company. On the lower level of the Domain Name System (DNS), nevertheless, there are lots of other records, such as A and MX. The first one reveals which server deals with the site for a given Internet domain and is always an IP address (18.104.22.168), while the latter indicates which server deals with the e-mails and is always an alphanumeric string (mx1.domain.com). As an example, when you enter a domain in your browser, your request is directed through the global DNS system to the provider whose NS records the domain name uses and from there you may be directed to the servers of a different company if you have set an IP address of the latter as an A record for your domain address. Having independent records for the website and the e-mails means that you could have your site and your emails with 2 different providers if you'd like.