Whenever you add a domain name as hosted in some account, you usually set a pair of Name Servers to direct it to that particular provider. On their end, 3 records are set up automatically when the Internet domain is added - one A record and two MX records. The former is a numeric address, or IP address, that “tells” the domain name where its site is, while the other two are alphanumeric and they indicate the server that manages the e-mails for that specific Internet domain. The website and the e-mail hosting are typically thought to be one thing, when they're actually two different services. Having different records for them will permit you to have them with different companies if you would like. For instance, some new service provider can have fantastic uptime for your site, but you might not want to switch your e-mails from your current host and by using an A record to point the domain to the first and MX records to have the emails with the second, you will get the best of both providers. These records are checked when you wish to open a website or send an e-mail - in either case, the service provider 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 right web/mail server will then be contacted and you will see the needed website or your email is going to be delivered.