phranque - 7:19 am on Mar 3, 2013 (gmt 0)
those 2 IP addresses "assigned by your host" are the IP addresses of the 2 nameservers assigned by your host.
they are NOT the IP address(es) of your web server, which is what the A record is all about.
your host is probably dynamically assigning the IP address of your web server so it is "managing the the A records dynamically", so to speak, within its own 2 nameservers.
you will probably need to do something similar with dnsever by using their dynamic dns service.
in addition, your hosts nameservers need to know about the dnsever nameservers and vice versa.