I am working on a tiny application that checks whether the network settings of a (Linux) machine are correct enough to complete certain tasks. IPv6-wise I'm checking whether the machine nameserver can be queried for AAAA records. Many DNS servers embedded in ADSL gateways/routers have problems with them. Around the net I found dozens of posts talking about IPv6 problems born out of misconfigured machines. Can you give me hints about these misconfigurations and how I can replicate them? For example, how can I replicate and spot the typical (?) "IPv6 is enabled, somehow the connection provider offers IPv6 connectivity but it is broken after the first router"? Other examples of "misconfiguration" are welcome. PS: where is the "Preview" button?