Whenever you add a domain name as hosted in some account, you normally set a pair of Name Servers to point it to that particular service provider. On their end, 3 records are created automatically when the domain address is added - one A record and two MX records. The first one is a numeric address, or IP address, that “tells” the domain address where its site is, while the other two are alphanumeric and they reveal the server that handles the e-mails for that specific domain address. The site and the email hosting are generally considered to be one thing, when they are in fact two different services. Having separate records for them will enable you to have them with different providers if you want. As an illustration, some new service provider might have exceptional uptime for your website, but you may not want to switch your emails from your current host and by employing an A record to point the domain name 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 e-mail - either way, the company 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'll see the needed site or your email will be delivered.