NxFilter is a freeware web-filter designed for enterprise environment. It started as a dns-filter. Now it provides web-proxy based filtering as well. NxFilter can do everything you can expect from a dns-filter or a web-filter.
Traditionally we made a web-filter based on HTTP proxy server. There are many commercial products based on Squid proxy. But with this approach you might have a serious latency problem on your network. This is because your web traffic needs to go through one point in your network that is your web-filter and it becomes a bottle neck in your network.
This latency problem gets bigger when you have bigger number of users. But there's another approach. That's DNS filtering and NxFilter is a dns-filter. It's basically a forwarding DNS server with filtering ability. Since it uses light weight DNS protocol there's no need to have your traffic going through anywhere. You get no latency problem with NxFilter.
NxFilter is a DNS filtering software. You can filter and monitor Internet activity in your network with NxFilter. It is also capable of detecting and blocking malware and botnet based on DNS packet inspection.