By Kieren McCarthy, The Register.co.uk

Google has become a registrar - a company allowed to sell Internet domain names - but told us it has no current plans to sell any.

Last week, Internet overseeing organization ICANN and technical arm IANA, quietly approved Google's application and gave it ID number 895:

http://www.iana.org/assignments/registrar-ids

It is now entitled to sell any .biz, .com, .info, .name, .net, .org and .pro domains (but not .aero, .coop, or .museum). Interestingly though, a Google spokeswoman told us it has no plans to sell any at the moment.

The reason it paid a $2,500 application fee and $6,500 to cover six top-level domains is that it "wants to get a better understanding of the domain name system and so increase the quality of our search results". The email address it gives with relation to its new registrar status is dns-admin@google.com.

Google notes that Amazon did exactly the same thing nearly two years ago. At that time, a March 2003 article in the Wall Street Journal pointed out that the online giant had become a registrar and assumed that it was about to launch a domain name selling business. It set the industry off - but we are still waiting, 47 months later.

So the question is: why become a registrar if you're not going to sell domains? Speculation is rife.

One idea is that it has to do with Google's AdSense for Domains business, which aims at the domain name industry. Google's technology "understands the meaning" of domain names, the company says, and then ties it in with search terms that people type in its search engines.

Then of course there is the possibility that it will find a way of tying in all of its other new services and connecting them to a domain name sale. So, for example, you buy "All-in-one.com" through Google and it gives you Gmail, Blogger and whatever else in a bundle. It does a Microsoft of the internet by getting you to use all its software and services and so give itself an enourmous amount of power and control.

Plus, if Google was in charge of your domain, it has access to everything that comes in and goes out and could use it to tackle spam more effectively.

And then of course, there is the ongoing rumour that Google may be developing its own web browser (it owns www.gbrowser.com). And then the pie-in-the-sky idea that it may release its own operating system.

But leaving the Google-heads behind, what is clear is that if you become an accredited registrar you gain an extra level of access to the DNS system and that means you can have a look at the inner workings, experiment with a thing or two and come up with new ideas and improved services.

And if there is one thing Google really excels at, it is getting more than everyone else out of the internet infrastructure.