Each domain that's registered and hosted has quite 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 illustration, the A record of a domain name is its IP address i.e. this record shows where the web site is situated; the MX records show where the e-mails are managed, while through an SRV record you can use a domain for unconventional purposes, for instance a Voice-over-IP service. To be able to set up and modify particular records enables you to have different services with different companies if, for example, your present host provides dependable web hosting, but has issues with the email service, or you simply prefer to get a particular service from a particular company. Although you can create and edit these records freely and with no restrictions as you own a given domain, some companies charge extra to give you this option.