Every single domain that is registered and hosted has a great deal of DNS records - some of them are set up automatically when you host a domain, others can be set up by hand if required. For example, the A record of a domain is its IP address i.e. this record reveals 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 name for unconventional purposes, for instance a Voice-over-IP service. The ability to create and modify certain records enables you to have different services with different providers if, for illustration, your current host provides good web hosting, but has difficulties with the e-mail service, or you simply prefer to get a specific service from a specific company. Although you can create and modify these records freely and with no restrictions as you own a given domain address, many companies charge extra to give you this option.