Each domain that is registered and hosted has a great deal of DNS records - some of them are set up automatically when you host a domain, others can be created by hand if needed. As an example, the A record of a domain is its IP address i.e. this record reveals where the website is situated; the MX records show where the emails are stored, while with an SRV record you can use a domain for unconventional purposes, like a Voice-over-IP service. Being able to create and modify specific records permits you to have different services with different providers if, for example, your present host provides stable web hosting, but has problems with the email service, or you simply prefer to get a certain service from a particular company. Though you must be able to set up and modify these records freely and with no limitations as you own a given domain name, lots of companies charge extra to give you this option.