This recipe describes adding entries to this routing table that will not persist following a reboot. These temporary routes are useful during troubleshooting or when making changes to the network topology.
route add 192.168.1.1 mask 255.255.255.0 172.16.100.1
route add 192.168.15.123 172.16.10.1 metric 10
Windows will automatically guess which interface is most appropriate for the given route. If you are dissatisfied with Windows's guess, the optional if {interface} parameter can be used. To specify that the previous route example should use interface 2 (identified with the hexadecimal value 0x2 in the route print command)
route add 192.168.15.123 172.16.10.1 metric 10 if 2
For example, if you were on the 192.168.1.0 network, and you had a gateway on 192.168.1.12 configured to access the 10.10.10.0/24 network, you would use a route add statement like this:
route ADD 10.10.10.0 MASK 255.255.255.0 192.168.1.12
Your routing table should now reflect that change, and all traffic to the 10.10.10.x range will now be sent over to the gateway machine.
The route add change will only stick across reboots if you add it with the -p flag, as in the following:
route -p ADD 10.10.10.0 MASK 255.255.255.0 192.168.1.12
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ROUTE [-f] [-p] [command [destination] []
The –f switch is optional. This switch tells Windows to clear the routing table of all gateway entries. If the –f switch is used in conjunction with other commands then all gateway entries will be cleared prior to executing other instructions within the command.
The –p switch makes a specified route persistent. Normally, when a server is rebooted then any routes that you specify via the ROUTE command are removed. The –p switch tells Windows to keep the route even if the system is rebooted.
The command portion of the ROUTE command’s syntax is relatively simple. The command set consists of four options PRINT, ADD, DELETE, and CHANGE. I’ve already shown you the ROUTE PRINT command, but even the ROUTE PRINT command has other options. For example, you can use wild cards with this command. For instance, if you only wanted to print routes pertaining to the 192.x.x.x subnet, you could use the command ROUTE PRINT 192*.
The ROUTE DELETE command works very similarly to the ROUTE Print command. Simply enter the ROUTE DELETE command followed by the destination or the gateway that you want to delete from the routing table. For example, if you wanted to remove the 192.0.0.0 gateway, you could enter the command ROUTE DELETE 192.0.0.0.
The ROUTE CHANGE and the ROUTE ADD commands have the same basic syntax as each other. When you enter this command, you must usually specify the destination, subnet mask, and gateway. You might also specify a metric and an interface, but that’s optional. For example, if you wanted to add a destination using the bare minimal syntax, you could do so as follows:
ROUTE ADD 147.0.0.0 255.0.0.0 148.100.100.100
In this command, 147.0.0.0 is the new destination that you are adding. 255.0.0.0 would be the subnet mask for the destination, and 148.100.100.100 would be the gateway address. You can extend the command with the METRIC and IF parameters. Doing so would look something like this:
ROUTE ADD 147.0.0.0 255.0.0.0 148.100.100.100 METRIC 1 IF 1
The metric parameter is optional, but it specifies the metric or number of hops for the route. The IF parameter tells Windows which NIC to use. In this particular case, Windows would use the NIC that’s bound to Windows as interface 1. If you don’t use the IF parameter then Windows will automatically search for the best interface to use.