Any time you add a domain name as hosted in some account, you normally set a pair of Name Servers to direct it to that particular provider. On their end, 3 records are created automatically when the Internet domain is added - one A record and two MX records. The former is a numeric address, or IP address, which “tells” the domain address where its website is, while the other two are alphanumeric and they reveal the server that manages the e-mails for that particular domain name. The website and the email hosting are often thought to be one thing, when they're in reality two different services. Having different records for them will permit you to have them with different providers if you want. For instance, some new service provider may have excellent uptime for your site, 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 emails with the second, you could get the best of both providers. These records are checked when you wish to open a website or send an email - in either case, the service provider whose name servers are used for the domain is going to 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 site or your email is going to be delivered.