Range my Cox IP addresses can take on?

Not to be confrontational, but why do you need this? Perhaps if I understand what you need it for I might be able to work out a solution. Are you trying to set a static IP? Firewall rule? Port forwarding?

It's for security reasons. When I travel to my second home, which also uses Cox, I would like to be able to log-in to my first home's network, whose router gives an option to specify a range of IP addresses to accept for incoming traffic. Thus, if I could know the range of IP addresses my second home's network could have, I could decrease the chances someone could login to my first home's router/network.

Ahh I see. I thought maybe we could work out something with DDNS or something simular. The problem isn't finding out what the range is NOW, thats doable, but rather how long it will stay that way. As the IPv4 pool becomes smaller and smaller, I have noticed the DHCP rotation increase, and sometimes entire new blocks opened or moved to different area's. 

If security is more of a concern then the possibility of it not working, you can use ARIN to get the block. First, while at your second home, go to this site to find out your public IP. Then go to ARIN and enter that IP in top right corner search. The Netrange will give you the block of IPs your pulling from, but if you want wider radius, then click on the IP to the right of "Parent" and that will show you the whole range. This still isn't complete, but its something. Use at your own risk. 

Wow, I totally forgot WHOIS gives the "NetRange" parameter. thanks