Whenever you add a domain name as hosted in some account, you typically set a pair of Name Servers to point it to that specific service provider. On their end, three records are set up 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 Internet domain where its website is, while the other two are alphanumeric and they show the server that deals with the emails for that specific domain address. The website and the email hosting are typically thought to be one thing, while they are actually two different services. Having independent records for them will allow you to have them with different companies if you wish. For instance, some new service provider may have superb uptime for your website, but you might not want to switch your e-mail messages from your current host and by employing an A record to point the domain address to the first and MX records to have the e-mails 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 e-mail - 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 are going to see the needed site or your email is going to be delivered.