The Dynamic Name System (DNS) is used to translate domain names (www.bestvpn.com) into numerical IP addresses (22.214.171.124). This translation service is usually performed by your ISP, using its DNS servers.
This means that your ISP can usually see and log which websites you visit, even if your IP address is obscured. To avoid this, VPN providers typically either provide their own DNS translation service, or use a third party service such as Google Public DNS or OpenDNS.
The problem with using such third party services is that they can be easily blocked (if censorship is the aim, as is commonly the case in China and Iran), or even worse, requests to them can be redirected. Known as DNS spoofing or DNS poisoning, this is a form of man-in-the-middle (MitM) attack often used by criminals (for example to redirect you from your legitimate online banking website to a forged site), or recently by the Turkish government to censor social networks and (scarily!) to identify political dissenters.
VyprVPN runs its own DNS service exclusively for its own customers to ensure that DNS requests cannot be monitored, logged or manipulated by third parties. VyprDNS is a zero logging service, and because Golden Frog runs the service on it on its own VPN severs, the geolocation errors that can occur when other VPN providers use third party DNS services located in different countries from their VPN servers are never an issue with VyprDNS.
Geolocation using third party DNS servers
Geolocation using VyprVPN and VyprDNS
VyprDNS is available automatically and for free to all VyprVPN customers. To find out more, why not head over to the Golden Frog website?