When you add a domain as hosted in some account, you usually set a pair of Name Servers to point 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 first one is a numeric address, or IP address, that “tells” the domain where its website is, while the other two are alphanumeric and they show the server that manages the emails for that specific Internet domain. The website and the e-mail hosting are often thought to be one thing, while they are actually two different services. Having different records for them will allow you to have them with different companies if you'd like. As an illustration, some new service provider might have fantastic uptime for your site, but you might not want to switch your emails from your current host and by employing an A record to point the domain to the first and MX records to have the emails with the second, you can get the best of both providers. These records are checked when you want to open a website or send an email - either way, the service provider whose name servers are used for the domain name will 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're going to see the needed website or your e-mail is going to be delivered.