I think the server change seems to have worked okay. Checking the blog access logs, I can see that I’m getting hits from systems other than mine. I’m still also getting a few hits on the old site but that should be trailing off.
The magic is down to something called the Domain Name System (DNS). When you type in or click on a URL, such as a web address, the first step your computer has to do is figure out what system you are trying to connect to. My server is identified to computers on the Internet not as blog.webden.org.uk but 188.8.131.52 (the IP – Internet Protocol – address). Your computer probably doesn’t know this directly but, since it has been configured for IP communications, it will know how to contact another system that can either give it an address it can understand or pass on the question.
Assuming you’ve got a decent Internet connection, your system will get an answer in a fraction of a second and can make the request. When it reaches my system, it will spot that you asked for ‘blog.webden.org.uk’ and give you the blog or the particular page on it you wanted. If you had asked for www.webden.org.uk, that would give you the same server but a different site. And, if you ask for the site by IP address, you will presently get a fairly useless default page. I need to decide which site to point that to although people generally go on URLs and not IP addresses.
What I had to do while testing was change entry in my hosts file so that my computer knew where to look even if the rest of the world was still going to the old server. Now I’m done, the address information will propagate round the Internet. By the end of the weekend, all requests for blog.webden.org.uk should hit the new server and I can retire the old one. Job done!