Whenever you add a domain name as hosted in some account, you usually set a pair of Name Servers to point it to that specific provider. On their end, three records are created automatically as soon as 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 site is, while the other two are alphanumeric and they indicate the server that manages the emails for that particular domain address. The website and the e-mail hosting are typically thought to be one thing, when they are actually two different services. Having independent records for them will permit you to have them with different companies if you would like. As an example, some new provider can have fantastic uptime for your website, but you might not want to switch your emails from your current host and by employing an A record to point the domain address to the former and MX records to have the emails with the second, you can get the best of both providers. These records are checked whenever you want to open a site or send an e-mail - either way, the company whose name servers are used for the Internet domain 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'll see the needed website or your e-mail is going to be delivered.