Every single domain 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 set up by hand if required. As an illustration, the A record of a domain is its IP address i.e. this record shows where the website is situated; the MX records reveal where the e-mails are managed, while through 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 specific records permits you to have different services with different companies if, for instance, your present host provides good web hosting, but has difficulties with the e-mail service, or you simply prefer to get a certain service from a specific company. Though you can create and edit these records freely and with no limitations as you own a given domain, some companies charge extra to give you this option.