Any time you add a domain as hosted in some account, you usually set a pair of Name Servers to point it to that specific company. On their end, three records are set up 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 name where its website is, while the other two are alphanumeric and they show the server that manages the e-mails for that particular domain name. The site and the e-mail hosting are generally regarded as one thing, while they're 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 company might have exceptional 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 Internet domain to the former and MX records to have the emails with the second, you will get the best of both providers. These records are checked when you wish to open a website or send an email - in any case, the service provider whose name servers are used for the domain name 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 are going to see the needed website or your e-mail will be delivered.