Show IP route

Everest63

Hi folks,
This is a subnetting question relating to the show ip route command
I'm on page 359 of the chapter IP Routing of Todd Lamme's book CCENT INCD1 Study Guide 100-105
I know quite a bit (sorry, no pun intended) about subnetting but there's always a question that can stump me when the subnetting question comes from a different angle.

P. 359

Based on the output of the routing table which interface will a packet with a destination address of 10.10.10.14 be forwarded from?

Gateway of last resort is not set

C 10.10.10.16 /28 is directly connected, FastEthernet0/0
L 10.10.10.17 /32 is directly connected, FastEthernet0/0
C 10.10.10.8 /29 is directly connected, FastEthernet0/1
L 10.10.10.9 /32 is directly connected, FastEthernet0/1
C 10.10.10.4 /30 is directly connected, FastEthernet0/2
L 10.10.10.5 /32 is directly connected, FastEthernet0/2
C 10.10.10.0 /30 is directly connected, Serial 0/0
L 10.10.10.1 /32 is directly connected, Serial0/0

The answer is:
The packet with destination address of 10.10.10.14 will be forwarded from C 10.10.10.8 /29 is directly connected, FastEthernet0/1

Isn't this a "What subnet does this host address belong to type of question?

Is there a quick & easy method to figure this out?

clarson

Isn't this a "What subnet does this host address belong to type of question? Yes, it is

looking for where 10.10.10.14 should be connected.

work your way down the connected networks.
10.10.10.16 10.10.10.16 is the network address (the lowest address on that network) so 10.10.10.14 isn't going to be on that network.
next connected network is 10.10.10.8. looks good. check the block size. /29 block size is 8. so the network is .8 - .15
So, 10.10.10.14 goes right there.

what is so hard about that.

blatini

Yes, and because it is that type of question that's the network it needs to go to.

The other networks don't have that address in their range.