Every registered domain has a minimum of two Name Server records which show where it is hosted i.e. by using these records you direct your Internet domain to the servers of a certain website hosting company. That way, you have got both your site and your emails handled by the exact same provider. On the lower level of the Domain Name System (DNS), on the other hand, there are lots of other records, like A and MX. The former shows which server manages the site for a given domain address and is always an IP address (220.127.116.11), while the second one indicates which server deals with the e-mails and is always an alphanumeric string (mx1.domain.com). As an illustration, whenever you enter a domain address in your Internet browser, your request is directed 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 a different service provider in case you have set an IP address of the latter as an A record for your domain address. Having separate records for the website and the emails suggests that you can have your website and your e-mails with two different providers if you wish.