When resolving domain names to IP addresses (DNS) while using a secure connection like VPN or TOR you should always make sure that your DNS requests are sent over the encrypted tunnel instead of an open network.
If your DNS requests are sent over an unencrypted network instead, this is called a DNS leak: Even though your actual traffic (the data you send to and receive from a server) is still encrypted, your ISP is able to see to which servers you are connecting to.
Whenever anonymity is critical to you it is important that you make sure that all traffic, including DNS requests are being sent through an encrypted network.
The Perfect Privacy software enables you to make sure that all DNS requests are encrypted so that no DNS leak occurs. This can be achieved with one mouseclick: It is as simple as activating the DNS Leak Protection checkbox.
Furthermore you can decide whether the protection will be active only while the tunnel is running, only while the VPN software is running or always active.