The Kill Switch and DNS Leak Protection are security features found in the ZneMate VPN desktop client for Windows. The features can be enabled and disabled in the settings menu in the client.
The Kill Switch
The Killswitch features prevent data leaks by making sure your device only have internet access if the connection is going through the VPN. Meaning that, if the VPN for some reason loses connection, no data will be processed on the device.
DNS Leak Protection
DNS, or Dynamic Name System, is used to translate a domain names into an IP address. A DNS server works a bit like a phone book and knows what IP address goes with what domain name.
When you want to open a website, the DNS server looks up what IP address you are "calling" and connect you to the server where that IP is hosted and open the right site in your browser. When you are not using a VPN, your ISP uses its own DNS servers find the website you are looking for.
When using ZenMate, all this is instead done within the VPN tunnel and your ISP cannot see what page you are visiting.
Unfortunately, it sometimes happens that Windows goes its own way and use the default settings. This means that the request is sent via the ISP's rather than through ZenMate and the ISP can see what page is visited. This is known as a DNS leak.
The DNS Leak Protection feature prevents this from happening by making sure that the DNS request cannot be performed by the native platform but only by ZenMate.