When you add a domain 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 created automatically as soon as the domain address 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 website is, while the other two are alphanumeric and they indicate the server that manages the emails for that particular Internet domain. The site and the e-mail hosting are typically regarded as one thing, when they're in fact two different services. Having independent records for them will permit you to have them with different providers if you'd like. As an illustration, some new provider may have exceptional 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 e-mails 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 e-mail - either way, the company whose name servers are used for the domain address 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 will see the needed site or your e-mail is going to be delivered.