Every registered domain has a minimum of two Name Server records that show where it is hosted i.e. by using these records you point your domain address to the servers of a certain website hosting company. In this way, you've got both your site and your emails handled by the exact same service provider. On the lower level of the Domain Name System (DNS), nevertheless, there are a number of other records, like A and MX. The first one shows which server deals with the website for a given domain and is always an IP address (184.108.40.206), while the second one shows which server deals with the emails and is always an alphanumeric string (mx1.domain.com). For example, any time you enter a domain name in your Internet browser, your request is sent through the global DNS system to the company whose NS records the domain 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 name. Having different records for the website and the e-mails means you could have your website and your emails with two different providers if you wish.