Any active domain name that's added in a hosting account features a number of records that allow it to function properly. In the typical case, the name servers (NS records) show where the Internet domain is hosted and they are set on the side of the registrar company, but on the lower level there are particular records set through the hosting company such as A (IP address of the website/server), MX (e mail server), SRV (employing a domain address for non-website purposes on a certain port number such as Voice-over-IP), and many others. Having access to these records and by being able to edit them, you can have your web site with company A and your e-mail messages with company B, for example. This gives you more overall flexibility because you can choose the best provider for every single one of these services and you don't need to stick with only one company. As soon as you select a hosting company, you have to make certain that you have access to all DNS records freely because some companies have an additional fee for this feature.