I've attempted to use some DNS services like OpenDNS, and no matter what I do the DNS queries don't return the expected results. Watching the packet traffic on my firewall, I can see the queries go out to the intended DNS server address and responses coming back, but the results are not as expected, for example, the OpenDNS test page always fails even though the requests appear to be going to their servers.
I suspect my ISP is intercepting DNS queries and sending them to their own servers. Is there a way to verify this? Is there something else I might be missing? I'm using 3G wireless service from Sprint.