Each registered domain name has at least 2 Name Server records that show where it is hosted i.e. by using these records you direct your domain address to the servers of a certain web hosting provider. In this way, you have got both your website and your e-mails managed by the same service provider. On the lower level of the Domain Name System (DNS), on the other hand, there is a variety of other records, like A and MX. The former shows which server deals with the website for a given domain and is always an IP address (220.127.116.11), while the second one reveals which server handles the emails and is always an alphanumeric string (mx1.domain.com). For instance, whenever you type a domain address in your browser, your request is sent through the global DNS system to the company whose NS records the domain name uses and from there you may be directed to the servers of another company in case you have set an IP address of the latter as an A record for your Internet domain. Having separate records for the site and the emails suggests that you can have your site and your e-mails with 2 different providers if you wish.