A Default Static Route is configured on the routers so the traffic can be transferred to a default route if there is no entry in the routing table for a specific network.

Before sending packets to the other networks, routers check their routing table. The router drops the packets if it is unable to find a specific route on which traffic should be sent. And when a router does not find the route in its routing table it sends the traffic to a default route, if that default route is configured. So basically, the traffic is sent out of the interface mentioned in the default route in the absence of an entry in the routing table for the traffic.

The default route is most useful when sending traffic to a public network like the internet because it is not possible to have the routing table for the entire internet. Hence, the default route helps the routers to send the packets going out to the internet.

In the local area network, when the destination address is not available in the local network then the data is sent out of the default gateway which is then routed to the other networks by routers; similarly, the default route helps to find the destination which is not available in the routing table.

In the below lab, we will create a default route on the router to enable routing between different subnets.

The below network scenario is not common in the real world, we have just created this lab to show how the default route can route the traffic without the routing table however we can test the real default route in action if we configure the default route on the router which is connected to the internet. In the packet tracer lab, we cannot emulate the internet so we are testing the default route in a simple network.

Note: we will only create a default route on the router. After that, the router should be able to route traffic. You can ping router 4 from router 0 to check routing in action.

Command explanation – IP route 0.0.0.0 0.0.0.0 192.168.1.2

In the above command 0.0.0.0 means that any IP address with any subnet mark should be sent out of interface 192.168.1.2 if a route is not present in the routing table.

Once we configure the default route, we can see the default route in the routing table with the S* symbol while static routes are shown with just the S symbol.

Before configuring the default route, you will see that gateway of last resort is not set however once the default route is configured, the gateway of last resort is the router’s interface from which traffic will be sent out.

 

default static route

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Lab Tasks

  1. Create a default route on router 0 and 1 to reach network 192.168.3.0/24 and 192.168.4.0/24
  2. Create a default route on router 2 to reach network 192.168.1.0/24
  3. Create a default route on router 3 and 4 to reach network 192.168.1.0/24 and 192.168.2.0/24
  4. Test Routing by pinging router 4 from router 0

Lab Configuration

Task 1

Router 0

Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.2

Router 1

Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.2.2

Task 2

Router 2

Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.2.1

Task 3

Router 3

Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.3.1

Router 4

Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.3.1

Task 4

Router 0

Router#ping 192.168.4.2