Enterprising would-be online money-makers have been able to exploit the window of time that allows them to test a domain name - in this case for its ability to generate advertising revenue - before they actually pay for the domain, according to the Associated Press.

The five-day grace period was originally meant to allow people who had made a mistake when purchasing a domain name, such as typing the wrong name, to fix their mistakes. But those looking to set up spam sites to generate advertising revenue are taking advantage of this loophole to sift through domains, looking for those that could generate the largest income.

That practice, known as "domain tasting," means up to six million domains are unavailable to legitimate buyers at any given time. The rise of automated systems that can have a site live within hours of its being registered means such scam artists are able to cycle through a larger pool of domains to "taste" in a short period of time.

At least one company that engages in "tasting" has defended the practice as perfectly legal, contending that many leading companies have done it, though none were actually named.