Generally the web page author is nominally in charge of moving a web
page from one IP server address to a different IP server address. If
this happens, they could change (perhaps through a script) all the links
on the page to use the new IP address just like they currently renumber
all the other things which must change when moving.
In general, people clicking on URL's have no idea what the anchor URL
is. Unless you look at the HTML source, you see the text not the URL.
Of all the protocols which use DNS, HTTP/HTML seems to be the easiest for
users to use something else. TELNET, FTP, and SMTP have much more
user-visible DNS names, and are therefor much more difficult to change.
There are several inter-related issues (as always):
- Long-term stability of the identifier
- Global uniqueness (within the relevant domain)
- Easy for humans to remember
- Simple for machines to process