It resolves human-readable domain names such as www.ccleaner.com into machine-readable IP addresses such as 154.65.36.76
On Windows apparently it works wether it is enabled or disabled, but when it is enabled, entries are cached (means saved). So the next time it needs to lookup (resolve) a previous resolved domain name into an address, it gets the address from its cache. That way it dont have to query the DNS server for the address everytime.
No ill effects? Yet in your screenshot none of the images loaded.
Yeah but you wouldn't have known that when I use Opera I don't allow images to load (which any Opera user would know looking at cached image icon next to the eyeball that has 100% at the upper right), remember I'm on dial-up and loading images takes ages.
I tried Opera 9 a few times but I just don't like it.
Opera 9.0 has to be the buggiest "stable" release version of Opera I've ever had the misfortune of using, although there have been other troublesome versions in the past. 9.0 has some serious problems from some webpages like Yahoo! TV not loading properly and being completely unusable, to all sorts of stuff that worked fine in 8.54 which is why I completely removed 9.0 and installed 8.54.