) You may also wish to add your own domain information to the file, in order to keep all of the zones in the same place.
It also keeps the file safe from accidental corruption.
Debian and other Linux distros already have a file called "local" so we'll use that as an example.
A standard format for DNS entries is called "Bind Format".
In most instances of bind, there are two files of interest: the master config file (called on most machines) and the "zone" file associated with each administered domain (usually called something like "dns").
Most of the actual content of this file is not important, as it is not serving up information for a "production" domain.
(You need to be much more careful with an actual domain!
A list of domains that are known to be used to propagate spyware and malware are listed in Bind and Windows zone files.
The domains are loaded onto an internal DNS server.
The DNS server, beleiving it is an "authority" for the that zone, will answer the query instead of querying another dns server for the answer.
The desktop receiving the answer doesn't know that the ip address received is not "valid".
dns is the file containing information about the hosts in the "coolwebsearch.com" and "gator.com" domains.