I installed Windows 7 on two computers this week here at home. They are both connected to the same NAT router (which connects me to my DSL connection), so this is a VERY conventional setup.
IPconfig shows, that both systems have an IPv4 as well as IPv6 running, both consequently also have two addresses (an IPv4 as well as an IPv6 address), though the connection to the internet is IPv4 only.
Now I just noticed, that if I ping computer 1 from computer 2 the name resolves to an IPv4 address (192.168.1.12). If I ping in the other direction the name is resolved to an IPv6 address (fe80::281a:b9de:5543:3b62%11). I have installed both systems from the very same CD and I didn't do anything special nor different regarding networking. So why is one PC resolving system names using IPv6, the other IPv4?
In principle I couldn't care less which IP version the systems are using as long as connections work ok, but I am using a file synchronization utility that apparently compares addresses and if the subnets of the two system don't match switches to a mode where it synchronizes via a proxy out somewhere in the network.
If it detects, that both systems are in the same subnet, they connect directly which then runs much, much faster. That's why I need both system to use the same subnet and hence they should both use the same default IP stack.
Can one change the preference or order of these stacks?