Router IP address overlaps with another network

[lena]

Hello everyone.

I am studying for ICND1 exam and found the question that I can not resolve.

There are 2 networks connected by RouterC:
NetworkA: 10.1.1.0/30 - with a server connected to a RouterC fa0/1 IP address 10.1.1.4
NetworkB: 10.1.3.128/25 - with 64 hosts connected to the RouterC fa0/2 IP address 10.1.3.1

the answer is: Interface fa0/2 has an IP address that overlaps with network 10.1.10/30.
I can not find how this networks overlap. May be the answer is incorrect?
Thank you for help

[DelVonte]

Hi Lena,

I don't seee any overlapping here, but 10.1.1.4 is incorrect for the network and subnet mask listed. The range would be 10.1.1.0 - 10.1.1.3 for a /30, with the first and the last being excluded. Maybe I'm missing something.

Please clarify the question adn/or IP addresses and subnets.


DelVonte

[lena]

Hello DelVonte,

You are correct about invalid IP address for fa0/1. That was another correct answer for this design.
But for overlaping I did the math and could not find any. That's why I put this question here - to find another opinion.
Looks like that answer about overlaping is incorrect.

Thank you for reply.

[Michael Law]

fa0/2 IP Address: 10.1.3.1 does not fall within the 10.1.3.128/25 subnet. It falls within the 10.1.3.0/25 subnet. Therefore, the overlap exists there if 10.1.3.0 subnetwork is present.


Mike

[Keith Barker]

I agree with DelVonte -

There are several things amiss regarding the question. Neither Fa0/1 or Fa0/2 are in the correct subnets.
Let us know if there is different information.


Keith

[lena]

I do not have additional infornation on this question.
But after Michael answer I have another question:

If fa0/2 IP Address: 10.1.3.1 will be within the 10.1.3.0/25 subnet (will consider that 10.1.3.0 subnetwork is present instead of 10.1.3.128/25) how to calculate the overlap with 10.1.1.0/30?

Thank you

[Michael Law]

That's the thing: 10.1.1.0 /30 and (10.1.3.0 /24 or 10.1.3.128 /25) do not overlap. No matter what IP address falls within those two scopes, you will not have overlap. The question seemed flawed when you originally posted it because several IP addresses posted did not fall within the 2 specific subnets given. We can't give you an accurate answer if the question isn't accurate. Sorry.


Mike

[lena]

Thanks to everyone who replied to my question about ip address overlaps.

I found this question on the web site, tried to solve it, and was not sure that the answer about overlaping is wrong.

With your help I understand that this question and answers are incorrect.

[breezeby1]

by any chance does it cost any money to take these exams? and also if you don't pass them do you pay for them as well?