Each and every domain that is registered and hosted has quite a lot of DNS records - some of them are set up automatically when you host a domain, others can be created by hand if required. As an illustration, the A record of a domain address is its IP address i.e. this record reveals where the site is situated; the MX records reveal where the emails are handled, while using an SRV record you can use a domain name for unconventional purposes, including a Voice-over-IP service. Being able to set up and modify particular records allows you to have different services with different providers if, for illustration, your present host provides dependable web hosting, but has troubles with the e-mail service, or you simply prefer to get a particular service from a specific company. Though you can create and modify these records freely and with no limitations as you own a given domain, lots of companies charge extra to give you this option.