I am able to ping a device on a different subnet without passing through a L3 device. How?
Route Print on my local machine shows: 192.168.10.99 255.255.255.255 On-link 10.168.10.154 26
That is why, the On-link routes are accessible locally without any gateway, many times they are created when you connect via dial-up (to Avaya device maybe). You have to find out why this route is being created. Maybe it was just a left over or was added manually in the past as a persistent route, Try deleting the route, ping, then reboot and ping to see it was not created again somehow.
It looks to me like you have an additional ip address assigned to your NIC.
