Besides the performance gains, alternative DNS providers like OpenDNS and Google’s Public DNS can give you a security advantage by blocking phishing attempts and malicious Web sites.
The Domain Name System (DNS) is something we all use and depend on, yet don’t really
pay much attention to; if you have some time to investigate alternatives, you could
really enhance your network’s performance and security.
Before I tell you how to do this, let’s have a brief explanation of what DNS is. Think
of what a phone book does; it allows you to look up someone’s phone number so long as you
know the person’s name. The DNS does something similar for computers. For example, if you
type in “google.com” it translates that name into a sequence of four numbers, called an
IP address, which functions something like a phone number does. In this case,
google.com’s number is 18.104.22.168.
The overall Internet infrastructure has a series of master phone books, or DNS root
servers, located at strategic places around the world and maintained by a collection of
public, semi-public, and private providers. They talk to each other on a regular basis to
make sure that as we add new domains they are in sync.
Read “Improve Network Security with DNS Servers” at eSecurity Planet