Windows – Routing Decision with Two Default Gateways

gatewayroutingwindows

My windows machine has two network cards, both have default gateways. How does windows determine which gateway should it access when sending a packet to a remote endpoint?

More precisely, here's my routing table:

    Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0         10.0.0.1      10.0.0.191       10
          0.0.0.0          0.0.0.0    192.168.1.254    192.168.1.38       20
         10.0.0.0    255.255.255.0       10.0.0.191      10.0.0.191       10
       10.0.0.191  255.255.255.255        127.0.0.1       127.0.0.1       10
   10.255.255.255  255.255.255.255       10.0.0.191      10.0.0.191       10
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1       1
      192.168.1.0    255.255.255.0     192.168.1.38    192.168.1.38       20
     192.168.1.38  255.255.255.255        127.0.0.1       127.0.0.1       20
    192.168.1.255  255.255.255.255     192.168.1.38    192.168.1.38       20
        224.0.0.0        240.0.0.0       10.0.0.191      10.0.0.191       10
        224.0.0.0        240.0.0.0     192.168.1.38    192.168.1.38       20
  255.255.255.255  255.255.255.255       10.0.0.191      10.0.0.191       1
  255.255.255.255  255.255.255.255     192.168.1.38    192.168.1.38       1
Default Gateway:     192.168.1.254

When I send a ping to 10.0.0.180 it sends an arp through the network card associated with 10.0.0.191, while when I ping www.google.com it goes through 192.168.1.254. How does it decide?

Best Answer

Your ping to 10.0.0.180 goes out to 10.0.0.191 based on the 3rd rule

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