This prevents access to the listed sites by redirecting any connection attempts back to the local machine. Another feature of the HOSTS file is its ability to block other applications from connecting to the Internet, providing the entry exists.
You can use a HOSTS file to block ads, banners, 3rd party Cookies, 3rd party page counters, web bugs, and even most hijackers. This is accomplished by blocking the Server that supplies these little gems.
Host files can work as a two-edged sword, if you use the programs Ad-Aware, Spybot S&D and SpywareBlaster, you are aptly protected. Certain malware is known to change the settings of your hostfile, so that you cannot reach vital security sites, other than through url. If you check the integrity of a hostfile (checksum) or use a nice program like hoster, this will work fine on Win 98SE, so you can make your specific hostfile blending. In Win XP SP2 etc. your hostfile can slow things up, and must not be too large, there block files and Zone restriction will be a better option.
Using a browser with AdBlocking will give similar results, in alternate browsers use Adblock plus.
Editors Note: in most cases a large HOSTS file (over 135 kb) tends to slow down the machine. This only occurs in W2000 and XP. Windows 98 and ME are not affected.
To resolve this issue (manually) open the “Services Editor”
Start | Run (type) “services.msc” (no quotes)
Scroll down to “DNS Client”, Right-click and select: Properties
Click the drop-down arrow for “Startup type”
Select: Manual, click Apply/Ok and restart.
After testing a lot of configurations, I’d rather let the hosts file as it is (without slowing down my system) and use only the SpywareBlaster and IE-Spyad blocks into the IE settings. PeerGuardian is a very good application to block access (inbound) from other sites.