Whenever you add a domain as hosted in some account, you normally set a pair of Name Servers to direct it to that particular service provider. On their end, 3 records are created automatically right after the Internet 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 domain. The website and the email hosting are often thought to be one thing, while they are actually two different services. Having independent records for them will permit you to have them with different companies if you would like. As an example, some new service provider might have fantastic uptime for your site, but you may not want to switch your e-mail messages from your current host and by using an A record to point the domain name to the former and MX records to have the e-mails with the second, you could get the best of both companies. These records are checked whenever you want to open a website or send an e-mail - in any case, 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 right web/mail server will then be contacted and you're going to see the needed site or your e-mail will be delivered.