Every single registered domain has at least 2 Name Server records that show where it is hosted i.e. by using these records you point your domain name to the servers of a particular website hosting provider. That 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), nevertheless, there are a number of other records, such as A and MX. The first one reveals which server manages the site for a given domain and is always an IP address (22.214.171.124), while the latter shows which server deals with the emails and is always an alphanumeric string (mx1.domain.com). For example, any time you type a domain name in your Internet browser, your request is directed through the global DNS system to the provider whose NS records the domain uses and from there you could be forwarded to the servers of another service provider provided you have set an IP address of the latter as an A record for your domain address. Having different records for the website and the emails means that you may have your site and your e-mails with 2 different providers if you'd like.