>> The non-NetTalk app is 2X, a management shell around terminal services. I don't know how I would bind this app to one of the IP's.
then it is likely bound to all IP's and so is likely the cause of the problem. You can obviously contact the vendor and ask about binding, or use a different server.
>> As for the Rackspace server, IIS was not installed by default so I'm not sure if there is anything else on port 443 on this machine.
Interesting - it may have changed - but on our rackspace machines IIS was installed, and had to be manually uninstalled.
>> However, I have a partial solution. I simply moved the 2X application, which communicates over SSL, to a non-standard port. Now that 2X is not using port 443, my secure NetTalk app works as expected.
cool.
>> It was my understanding that an IP address/Port combination was a unique socket. I thought IP1:443 would be unique from IP2:443. That is, I thought 2 different IP's could use the same port. Each of my IP's is now on it's own NIC.
yes, each ip/port is a unique socket. Yes programs (by default) gobble up _all_ ip's on that port if given the chance. (including nettalk servers.)
You don't (as far as I know) need multiple NIC's. windows allows you to assign multiple IP addresses to a single NIC.
the key is the "binding". By default pretty much all programs will "bind" to all available IP addresses. (again, nothing to do with NICs). In order to split them apart, so you get separation, you _must_ bind _all_ the programs to a single IP address. If you absolutely positively cannot bind one of them, then it has to be started _after_ all the others. (that in itself can be tricky to do, especially on a server.)
Cheers
Bruce