Any active domain name that is added in a hosting account features a variety of records that permit it to work properly. In the general case, the name servers (NS records) show where the domain is hosted and they are set on the side of the registrar company, but on the lower level there are certain records set through the hosting company like A (IP address of the website/server), MX (e mail server), SRV (employing a domain name for non-website purposes on a specific port number such as Voice-over-IP), and so on. With access to these records and by being in a position to modify them, you can have your site with company A and your emails with company B, for example. This offers you more independence as you can select the best provider for every single one of these services and you do not have to stick to one company. As soon as you choose a hosting company, you have to make certain that you can access all DNS records freely because some companies have an additional fee for this function.