Each entry in a routing table provides a routing choice that can be used when the incoming packet meets a specified condition.
In this case the condition for each routing statement is whether the destination address for the incoming packet falls within a particular IP network, and they have given you some test addresses and asked you to say which routing rule would be applied to each one.
So what you have to do is look at each routing statement in turn and use the submet mask supplied to expand it out to find the range of IP addresses it includes. Once you've done that it will be easy to see which of the routing statements will apply to each of the test addresses.
The final twist in the tail is that if there is more than one routing statement that could apply to a given address then we can assume that it is the most specific (narrowest) match that will be used. Hence 172.16.1.1 falls within multiple routing statement ranges, but the most specific one to that address is 172.16.1.1/32 so that is the one that will be preferred.
Does that make sense?
Re: Finding the matching route on a router - please help
10 years 4 months ago #29773