Determining Current IPSTAG For a .co.uk Domain
So, what is the IPSTAG? You can think of it as a code that attaches your domain to a particular Internet Service Provider (ISP). Whoever has the IPSTAG is the organisation that has ultimate administration control of the domain.
Typically you would change IPSTAG only when changing your ISP - but how would you know it's changed? The solution is with the registrar themselves - Nominet provide a WHOIS facility to query various aspects of any domain you wish.
For example, the following link queries our own domain for registration details:
The section of most interest is here:
Internet Engineering Limited t/a Hosting UK [Tag = INTERNETENG]
In this case, the IPSTAG is INTERNETENG