When you add a domain as hosted in some account, you usually set a pair of Name Servers to point it to that specific service provider. On their end, 3 records are created automatically right after 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 website is, while the other two are alphanumeric and they show the server that handles the emails for that particular Internet domain. The site and the e-mail hosting are generally regarded as one thing, while they are in fact two different services. Having different records for them will permit you to have them with different companies if you'd like. As an illustration, some new provider can have exceptional uptime for your site, but you might not want to switch your e-mails from your current host and by employing an A record to point the Internet domain to the first and MX records to have the emails with the latter, you can get the best of both companies. These records are checked whenever you want to open a site 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 will see the needed site or your e-mail will be delivered.