Any time you add a domain as hosted in some account, you usually set a pair of Name Servers to point it to that particular company. On their end, 3 records are set up automatically when the domain name is added - one A record and two MX records. The first one is a numeric address, or IP address, which “tells” the domain address where its website is, while the other two are alphanumeric and they reveal the server that handles the e-mails for that particular domain. The website and the e-mail hosting are generally regarded as one thing, when they are in fact two different services. Having different records for them will permit you to have them with different companies if you would like. For instance, some new service provider could have exceptional uptime for your site, but you may not want to switch your emails from your current host and by employing an A record to point the domain address to the former and MX records to have the e-mails with the second, you will get the best of both companies. These records are checked when you wish to open a site or send an e-mail - in either 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 are going to see the needed website or your e-mail will be delivered.