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 specific service provider. On their end, three records are created automatically when the domain name is added - one A record and two MX records. The former is a numeric address, or IP address, that “tells” the domain where its website is, while the other two are alphanumeric and they indicate the server that deals with the emails for that particular domain name. The website and the e-mail hosting are usually thought to be one thing, while they are in fact two different services. Having independent records for them will enable you to have them with different providers if you would like. For instance, some new provider might have outstanding uptime for your website, but you may not want to switch your e-mail messages from your current host and by employing an A record to point the domain name to the first and MX records to have the emails with the latter, you could get the best of both companies. These records are checked whenever you want to open a website or send an email - in any case, the service 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 have set records different from their own, the right web/mail server will then be contacted and you will see the needed site or your e-mail will be delivered.