Each and every domain name 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 created by hand if needed. For example, the A record of a domain name is its IP address i.e. this record shows where the site is situated; the MX records reveal where the e-mails are managed, while using an SRV record you can use a domain for unconventional purposes, for instance a Voice-over-IP service. The ability to set up and modify particular records enables you to have different services with different providers if, for example, your current host provides stable web hosting, but has problems with the e-mail service, or you simply prefer to get a specific service from a certain company. Even though you can create and edit these records freely and with no limitations as you own a given domain address, some companies charge extra to give you this option.