Any time you add a domain name as hosted in some account, you normally set a pair of Name Servers to point it to that particular provider. On their end, three records are set up automatically the moment 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 where its site is, while the other two are alphanumeric and they show the server that deals with the emails for that specific domain address. The site and the email hosting are often thought to be one thing, while they're actually two different services. Having different records for them will allow you to have them with different companies if you want. As an illustration, some new provider might have fantastic uptime for your website, but you may not want to switch your e-mails from your current host and by employing an A record to point the domain address to the first and MX records to have the e-mails with the second, you could get the best of both companies. These records are checked when you wish to open a website or send an e-mail - in any case, the 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've set records different from their own, the right web/mail server will then be contacted and you're going to see the needed site or your e-mail is going to be delivered.