It gets tricky because there are two cameras with different internal IPs. If you can create a different hostname for each camera it will simplify things. Externally they can both resolve to the same IP.
Populate the hosts table on the 3548 with the internal IPs, for example:
host cam1.thatwebsite.com 192.168.1.101
host cam2.thatwebsite.com 192.168.1.102
Configure your 3548 to point to your normal outside resolvers:
name-server 220.127.116.11 18.104.22.168
Set your dhcp server to use the internal gateway of the 3548 as its DNS resolver.
Now from the inside, going to the URL for cam1.thatwebsite.com will resolve to the local inside IP.
I actually have 6 cameras, so it's a little bit more complicated that I guess I let on.
Your answer is correct.
Unfortunately this won't really help me as I was trying to do this without have to setup all 6 cameras, twice in my NVR app.
I was really looking for something that I could do that would allow me to just use one address that could be addressed both internally and externally.
Just an FYI - During my research there were a couple documents that used including: https://supportforums.adtran.com/docs/DOC-2287#comment-2857
The command ip debug dns-proxy does not work.