What is the Class A, B, or C network of the following address:
Sat Apr 21, 2012 2:51 pm
Sat Apr 21, 2012 6:56 pm
R3 is configured to use classful routing. With classful routing, the router first matches the Class A, B, or C network number in which a destination resides. If the Class A, B, or C network is found, Cisco IOS Software then looks for the specific subnet number. If it isn't found, the packet is discarded, as is the case with the ICMP echoes sent with the ping 18.104.22.168 command. However, with classful routing, if the packet does not match a Class A, B, or C network in the routing table, and a default route exists, the default route is indeed used--which is why R3 can forward the ICMP echoes sent by the successful ping 10.1.1.1 command.
In short, with classful routing, the only time the default route is used is when the router does not know about any subnets of the packet's destination Class A, B, or C network.
Sat Apr 21, 2012 10:59 pm
So, if the destination address is 22.214.171.124, the classful B network is 126.96.36.199, correct? Since there aren't any subnets of this network in the routing table, shouldn't the ping 188.8.131.52 succeed by using the default route?
Sun Apr 22, 2012 1:30 am
Sun Apr 22, 2012 11:39 am
mellowd wrote:It should be using the default route yes, but what about return traffic? What does the route table look like on the responder? What happens when you traceroute? What happens when you ping with a source address of your Ethernet interface?