Every single domain that's registered and hosted has a great deal of DNS records - some of them are created automatically when you host a domain, others can be set up by hand if required. As an example, the A record of a domain name is its IP address i.e. this record reveals where the web site is located; the MX records show where the emails are handled, while through 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 certain records allows you to have different services with different companies if, for instance, your current host provides dependable web hosting, but has issues with the email service, or you simply prefer to get a certain service from a particular company. While you can create and edit these records freely and with no restrictions as you own a given domain address, many companies charge extra to give you this option.