Any time you add a domain name as hosted in some account, you typically set a pair of Name Servers to direct it to that specific service provider. On their end, 3 records are set up automatically the moment the Internet domain is added - one A record and two MX records. The former is a numeric address, or IP address, which “tells” the Internet domain where its website is, while the other two are alphanumeric and they indicate the server that manages the emails for that particular domain name. The website and the email hosting are often thought to be one thing, when they're in fact two different services. Having separate records for them will allow you to have them with different companies if you'd like. As an example, some new company might have exceptional uptime for your website, but you might not want to switch your e-mail messages from your current host and by using an A record to point the domain to the former and MX records to have the emails with the second, you could get the best of both providers. These records are checked when you wish to open a site or send an e-mail - in any case, the company whose name servers are used for the Internet domain is going to be contacted to retrieve the A and MX records and if you have set records different from their own, the correct web/mail server will then be contacted and you'll see the needed site or your email will be delivered.