I wanted to buy the domain com.co.uk the other day, however it doesn’t look like it’s possible.

I done an Whois and this is what the output shows:

Error for "com.co.uk".

This domain cannot be registered because it contravenes the Nominet UK
naming rules. The reason is:
third-level domains may not be identical to a top-level domain.

The question is, why can we not buy a third level domain which is identical to a top level domain? Also, is there a way to get this domain or not?

  • 4
    Every registry has certain naming rules in place (i.e. which domains can be registered and which can't). It looks like the UK NIC doesn't allow the name com to be registered. – tex Jan 22 '18 at 10:29
  • 2
    Anti-Abuse most likely, they do not want www.paypal.com.co.uk – Jacob Evans Jan 22 '18 at 13:29

Many of the non-US registries use the country code as the last part of the domain and use .co for companies (.co.uk). I don't believe any other than US registries use the domains .com, .net, .org and such. I think the error message is telling you that the registry cannot use a top level domain designation to create a domain that really includes 2 top level designations -- both the .com and the .uk count as top level.

You may be able to purchase a US domain with the .com designation, and also a UK domain using the .co.uk designation. Just depends on what the name is and if it is taken in the USA.

  • This is a very US-centric answer full of approximations. Domain names start with a TLD. Per design, there are ccTLDs which are country codes, and gTLDs (g is for generic) such as com, net, org, etc. Not all gTLDs are run by "US registries", for example .TEL and .NAME (at its beginning) were not. But this is mostly irrelevant to the syntax or form of domain names. Some registries only sells third level domain names, some second levels and some both at the same time (and some went even further than 3 levels, like .US in the past). Registries policies dictate which names are allowed. – Patrick Mevzek Jan 24 '18 at 4:42

There is nothing technically to forbid you doing that, each node in the DNS tree is the apex of the whole zone below it.

But there are not only technical reasons.

First, the problems with "levels" is that it depends from the registry. Historically, you were only able to register .co.uk domain names because this is what the registry (Nominet) decided to allow, which is not uncommon among ccTLDs even if it becomes the exception. Now things have changed, and you can register directly under .uk.

Second, each registry decides what domain names are allowed or not in the TLD it provides. Each registry has it list of reserved domains (not allowed at all) and/or premium domains (available under certain conditions such as eligibility rules or specific prices).

You should have asked the registry directly why the specific domain of your wishes is not available.

For gTLDs you can find from example here: https://www.icann.org/resources/pages/reserved-2013-07-08-en domain names reserved in all new gTLDs, and in the past, registries had prohibition to allow registration of other gTLDs as labels in their own gTLD, but the set of them was small.

As for .co.uk if you read the Rules of Registration at https://nominet-prod.s3.amazonaws.com/wp-content/uploads/2015/10/Rules_June_2014.pdf section 5.6 clearly states:

For a combination of policy and continuing technical reasons the Characters "com" and "uk" shall not be permitted as an SLD or a Third Level Domain within co.uk, me.uk, org.uk or net.uk.

So, until the registry decides to amend their rules, your wish will never be granted.

Now the (rhetorical) question would be: why do you care so much about this particular domain name, and why not settle for any other one?

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