When you add a domain name as hosted in some account, you typically set a pair of Name Servers to direct it to that particular company. On their end, three records are set up automatically the moment the domain name is added - one A record and two MX records. The former is a numeric address, or IP address, that “tells” the domain address where its website is, while the other two are alphanumeric and they indicate the server that manages the e-mails for that specific domain address. The website and the e-mail hosting are generally thought to be one thing, when they are in reality two different services. Having separate records for them will enable you to have them with different providers if you wish. As an example, some new provider may have outstanding uptime for your website, but you might not want to switch your e-mail messages from your current host and by employing an A record to point the Internet domain to the first and MX records to have the e-mails with the latter, you can get the best of both companies. These records are checked when you want to open a site or send an email - in either case, the company whose name servers are used for the domain address will be contacted to retrieve the A and MX records and if you've set records different from their own, the correct web/mail server will then be contacted and you'll see the needed website or your email is going to be delivered.