I stumbled on this post, not sure how.
I didn’t know about OpenDNS but it seems like a strange idea; after all, why would someone not use the DNS server that came with their DHCP lease? Seems like a fairly simple idea, over-ride the DNS servers and force the choice to be to use the DNS servers that OpenDNS provides, but why would anyone care to do this on a PC by PC basis? That seems just totally illogical!
And the problem that the author of the blog (above) mentioned is fairly straightforward. PC comes on the Virgin Wireless network, attempts to go to a web page, sends out a connection request for a page (assume that it is from a cache of IP addresses) and receives a HTML redirect to a named page (asking one to cough up money). The HTML redirect mentions the page by name and that name is not cached and results in a DNS lookup which goes to OpenDNS. Those servers (hardcoded into the network configuration) are not accessible because the user has not yet coughed up said money. Conversely, If the initial lookup was not from a cached IP address then the DNS lookup (which would have been sent to OpenDNS) would have not made it very far (OpenDNS’s server is not reachable till you cough up money). One way or the other, the page asking the user to cough up cache would not have showed up.
So, could one really do this OpenDNS thing behind a pay-for-internet-service? Not unless you can add preferred DNS servers to network configuration without a reboot. (the reboot will get the cycle of DHCP request going again, and on the high volume WiFi access services, DHCP request will automatically expire the previous lease).
But, to the more basic issue, why ever would someone enable this on a PC-by-PC basis? I can totally understand a system administrator using this at an enterprise level; potentially using the OpenDNS server instead of the ones that the ISP provided. Sure beats me! And there sure can’t be enough money in showing advertisements on the redirect page for missing URL’s (or there must be a lot of people who fat-finger URL’s a lot more than I do).
And, the functionality of being able to watch my OpenDNS traffic on a dashboard, I just don’t get it. Definitely something to think more about … They sure seem to be a successful operation so there must clearly be some value to the service they offer, to someone.