If you’re setting up a new web server or another device that’s going to be connected to the Internet and you want to put it through its paces before it’s live, or if you’re having trouble with spyware and adware networks, there’s an invisible file on your Mac that can help. It’s called the Hosts file, and this is how to use it.
The Domain Name System
When you type in the domain name of a web site you want to visit there’s a lot happening behind the scenes. Every web site, every service, almost every device connected to the Internet has a unique numeric address that tells all the other devices where it is — its TCP/IP address. The Domain Name System (DNS) translates those numeric addresses into something a bit more recognizable and memorable to humans, like, “www.imore.com” for example.
The first time you type in a web address, your Mac pings a DNS server — typically one automatically configured for you by your Internet Service Provider — to find out the TCP/IP address of t…