Updating the domain name nameserver settings on your 123-REG control panel is very straight forwards, but first let me tell you why the nameserver settings need to be updated.  The best simile I can think of is to imagine your website is a book and your domain name is a library index card.  Amongst other things, the index card has the name of the book (in our case the domain name) and where it is located (in our case a server or computer if you like that is permanently connected to the internet).  Search engines (Google et.al.) and Internet Service Providers (ISP's such as EE & BT) use the library card to find your book; If we move the book, we have to update the library card.  Chances are you are reading this because I have taken over the hosting of your website (book) and we need to update the domain name (library card) so as it points to my server.

 Anyhow, I think you have enough background, lets update the settings.

Step 1

Log In & Manage Domain

Log onto your 123-REG account, if you have more than one domain registered with them, select the domain you need to change and click the 'Manage' button.

123 REG manage account

Step 2

Advance Domain Settings

Scroll down the page until you reach the 'Advance Domain Settings' section and click 'Change Nameserver Settings'

123 REG change nameserver

Step 3

Nameserver Management

You only need to fill in the details for Nameserver 1 & Nameserver 2, the details are as follows:

Nameserver 1:  ns1.316.xenserve.com

Nameserver 2: ns2.316.xenserve.com

Leave Nameserver 3 & 4 blank (if there is information in these boxes, delete then and click UPDATE when done.

THAT'S IT, YOU'RE DONE!  You can go ahead and logoff 123-REG

123 REG nameserver management

Step 4

DNS Propagation

Search Engines and ISPs cache the nameserver settings much the same way as the web browser on your computer caches images to make them load faster the next time you visit the same site.  It can take up to 24 hours sometimes even longer for the search engines and ISPs to refresh their cache with the new nameserver settings.

123 REG DNS propagation