When you add a domain name as hosted in some account, you usually set a pair of Name Servers to direct it to that specific company. On their end, three records are set up automatically when the Internet domain is added - one A record and two MX records. The first one is a numeric address, or IP address, which “tells” the Internet domain where its website is, while the other two are alphanumeric and they reveal the server that manages the emails for that particular domain address. The site and the e-mail hosting are often perceived as one thing, when they're actually two different services. Having separate records for them will permit you to have them with different companies if you would like. For instance, some new service provider may have excellent 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 name to the former and MX records to have the emails with the latter, you will get the best of both companies. These records are checked when you want to open a website or send an email - either way, the provider whose name servers are used for the domain address 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 e-mail will be delivered.