Every domain which is registered and hosted has a lot of DNS records - some of them are created automatically when you host a domain, others can be created manually if needed. As an example, the A record of a domain address is its IP address i.e. this record reveals where the web site is located; the MX records reveal where the emails are stored, while using an SRV record you can use a domain for unconventional purposes, such as a Voice-over-IP service. The ability to set up and modify particular records allows you to have different services with different companies if, for example, your present host provides dependable web hosting, but has problems with the e-mail service, or you simply prefer to get a particular service from a particular company. Even though you will be able to set up and modify these records freely and with no limitations as you own a given domain address, lots of companies charge extra to give you this option.