The first line has an AD of 1 so it will of course be used instead of the default route with the AD of 250. As long as the interface to which the default gateway is connected is up, the route with the AD of 1 will always stay as the default route in the routing table. You need a way to remove this route if 188.8.131.52 is unavailable so that is gets removed from the routing table and the default route with the AD of 250 will then be inserted into the routing table and used. To do this, you can setup SLA(s) and tracking and apply the tracked object(s) to the default route pointing to 184.108.40.206.
In essence, you need a way to remove the default route to 220.127.116.11 so the next route with a higher AD will really be a backup. This is true with routes tied to routers on the same subnet.
Good point and obviously its clear now.
It is a way to work just with static routes main and backup in a simple topology like this: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800ef7b2.shtml
ip route 0.0.0.0 0.0.0.0 18.104.22.168
ip route 0.0.0.0 0.0.0.0 22.214.171.124 250
It is likely that 126.96.36.199 and 188.8.131.52 will use the same interface so
ip route 0.0.0.0 0.0.0.0 fa0/0 184.108.40.206
ip route 0.0.0.0 0.0.0.0 fa0/0 220.127.116.11 250
would not help.
One solution would be to verify 18.104.22.168 responds to a ping. You can then create a SLA and add the track keyword to the first route statement.
If the SLA fails the route is removed and the second one takes effect.
I tested this and everythink works as it get described, but just for point to point conection: router to router (recomended serials).
Exemple for ethernet topology: R1>>>SW>>>R2
If you put a switch betwen this 2 routers and if you "unplug" the conection from one router to switch, the oposite router will (R2 lets supose) not change his interface status ( up for status/ up for protocol). I think the protocol remains up for R2 because we have the switch port conected to R2 interface so everythink will remain up/up (no matter what happens to R1), so the configuration from the link which i mentioned above will not work.
Anyway its clear that is no way other than "teach" the router to switch the route.