[BNM] Simple DNS question

[James Moss]

Hi Guys,

Ive been toying round with a new idea for a simple web app to develop in my
spare time.  One of the features would enable users to point their domain to
my servers so that they could access their account through
http://customdomain.co.uk or
http://www.customdomain.co.uk<http://www.users-own-custom-domain.co.uk>instead
of
http://username.webapp.com. Pretty straight forward so far.

Users would obviously have to log into their domain control panel and point
their www A records towards the IP address of my server.

However the bit im wondering about - What if I change server IP 6 months
down the line to upgrade to a faster/bigger/cheaper host?  Will I need to
get all my users to point their A records to a new IP address? Can I get
them to point their A records to a hostname (under my control, pointing at
my server) instead of an IP address so that if I move my server to a new IP
address I would just have to change that one hostname instead?

Is there another easier way of doing this which im missing?

-- 
James Moss | Developer
Solv.IT | 01273 25 20 24