Each domain name which is 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 manually if needed. For example, the A record of a domain is its IP address i.e. this record reveals where the site is located; the MX records show where the emails are managed, while through an SRV record you can use a domain address for unconventional purposes, including a Voice-over-IP service. Being able to set up and modify particular records enables you to have different services with different companies if, for instance, your current host provides dependable web hosting, but has problems with the email service, or you simply prefer to get a certain service from a certain company. Even though you should be able to create and edit these records freely and without any limits as you own a given domain name, a lot of companies charge extra to give you this option.