This week, we were discussing ccTLD (country code Top Level Domain)
confusion at work – specifically in the context of the .om toplevel
domain, which apparently is used for tricking people into visiting
foo.co.om instead of foo.com.
This led me to dig a little more into how exactly the ccTLDs for each
country are assigned. RFC 1591
tells us that they are taken straight from
ISO-3166. However, as
always, there are exceptions. There are a handful of unused ones from
small, obscure regions round the world (including, amusingly, .um and
.eh) – but there is one rather large exception. The ISO-3166
country code for the United Kingdom is GB, but the domain used by
them is the well-known .uk.
You’d think the story ends there, but it doesn’t. Apparently .gb was
created and used at some point, and so it is still available from DNS
root (although not open for registration). I think this technically
makes the UK the only country to have two ccTLDs. And there is a
dwindling number of servers out there that still answer serve DNS
records over the .gb domain.
{~}$ dig +noall +answer A delos.dra.hmg.gb
delos.dra.hmg.gb. 86400 IN A 146.80.9.105