Whenever you add a domain 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 set up automatically as soon as 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 name where its site is, while the other two are alphanumeric and they show the server that handles the emails for that specific Internet domain. The site and the e-mail hosting are usually thought to be one thing, when they're in reality two different services. Having different records for them will permit you to have them with different companies if you'd like. As an illustration, some new provider can have excellent uptime for your site, 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 to the first and MX records to have the emails with the second, you can get the best of both providers. These records are checked whenever you want to open a site or send an email - in either case, the service provider whose name servers are used for the domain will be contacted to retrieve the A and MX records and if you've set records different from their own, the correct web/mail server will then be contacted and you will see the needed website or your email is going to be delivered.