cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
2953
Views
5
Helpful
19
Replies

IP routing question

Ahmed Malik
Level 1
Level 1

Hi,

    i am attaching an image regarding ip routing. can anyone tell me the exact answer for this as i am preparing for the ccna exam so here it is and do explain the answer to me as well.

Regards,

routing.JPG

19 Replies 19

Hi,

this is the 10.1.5.64/29 with a next-hop of 10.1.3.3

Regards.

Alain

Don't forget to rate helpful posts.

Florian,

Do not look at the IP addresses of the next hop routers when searching for the longest prefix match. Look at the addresses of the networks themselves. For the packet destined to 10.1.5.65, the longest matching entry is the network 10.1.5.64/29, as this network matches the destination in its first 29 bits, or in other words,

/29 = 255.255.255.248

10.1.5.65 AND 255.255.255.248 = 10.1.5.64

ANDing the destination IP address with the mask /29 yields the result 10.1.5.64 which matches the network 10.1.5.64/29, with the next hop 10.1.3.3. No other routing entry in the routing table gives you such a long match (or a match at all), so this one is the best.

Best regards,

Peter

hi peter,

thanks for your help. i think i got it.

regards,

florian

joeadiutori
Level 1
Level 1

For the network 10.1.5.0/24, there are 256 nodes.

For the network 10.1.5.64/29, there are 8 nodes.

The address in question is 10.1.5.65, and it falls into both networks above.  Since the /29 network is the smallest network, Cisco views this as the most precise network option, and will therefore forward the packet to the /29 network.  The answer is C.

Ahmed Malik
Level 1
Level 1

Thanks to all of you who helped me in this question.

regards,

Ahmed

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: