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 company. On their end, 3 records are created automatically as soon as the domain is added - one A record and two MX records. The former is a numeric address, or IP address, which “tells” the Internet domain where its site is, while the other two are alphanumeric and they show the server that manages the e-mails for that particular domain. The site and the email hosting are typically thought to be one thing, when they are in reality two different services. Having different records for them will enable you to have them with different companies if you wish. As an illustration, some new provider could have outstanding 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 to the former 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 e-mail - in any case, the service provider 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 correct web/mail server will then be contacted and you'll see the needed site or your email is going to be delivered.