Each registered domain name has no less than two Name Server records which show where it is hosted i.e. by using these records you direct your domain name to the servers of a certain website hosting company. In this way, you've got both your website and your e-mails managed by the very same provider. On the lower level of the Domain Name System (DNS), however, there is a variety of other records, like A and MX. The first one reveals which server handles the site for a given Internet domain and is always an IP address (18.104.22.168), while the latter shows which server manages the emails and is always an alphanumeric string (mx1.domain.com). As an illustration, when you type a domain in your browser, your request is sent through the global DNS system to the provider whose NS records the domain name uses and from there you may be sent to the servers of a different service provider provided you have set an IP address of the latter as an A record for your domain name. Having separate records for the site and the e-mails suggests that you may have your website and your e-mails with two different providers if you'd like.