Accept DNS Suffix

["Dominic Caputo" <dominic.caputo@xxxxxxxxx>]

I currently have an ISP that has multiple address ranges that I wish to 
accept in my iptables ruleset. Is it possible for me to use the DNS Suffix 
instead of the actual ip as they are currently dynamically assigned. e.g. 
iptables -s nsw.bigpond.net.au   (current assigned address is 
cpe-203-45-103-100.nsw.bigpond.net.au).

Alternatively if the above is not available would I be able to setup a 
dyndns account and get my dsl modem to update the account and within my 
iptables config set: iptables -s homegw.dynalias.com

Thanks

Dominic