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New Member

interview Question asked to me ...

I need answer of the below question.

1. What is FIB? what it does? where it is present? is it L3 switch, router and L2 switch.?

3.What is the differnece between Pagp and LCP?

4. What RPF, what is does.?

5. In ISDN my call is disconnected every 2 minutes, what is the problem, how will u troubleshoot?

6.What is happened when i connected a new switch to exiting switch ? e.g. A--B--C. A is in server mode and having vlan 3 & 4 and b is in client mode and C is new switch with vlan 5?

7.what is the command to block STP for a port to participate in STP? block communication between the to pc from the same vlan?


Re: interview Question asked to me ...


I will try to answer as much as possible.

1.FIB stands for forwarding information base.It is used for CEF switching which the cisco method for multilayer switching.

it is present in PFC card and it also depends upon the line cards u r using.

Its generally in L3 switches.

2.Pagp is cisco propritery and LACP is industry standard.

4.RPF =reverse path forwarding it is generally used to prevent multicat routing loops.


6.Nothing will happen but u need to take care about the revision number on the switch C if the trunk link is established and the revision number is less in switch c it will get updated as per switch A.

7.spanning-tree portfast.

New Member

Re: interview Question asked to me ...

Can you explain question 6 in depth. What about switch B, will it retains the vlan that it get from switch A or it will delete all previous vlan and add new vlan that is present created on Switch C. ( take both scenario rev no of sw A > sw C and rev no. SW A < SW B.

Re: interview Question asked to me ...


No it will retain the vlan info from switch A again as i said earlier it all depends upon the revision version and if the revision number in less then switch A both the switches will update their vlan info as per switch A.

In the scenario which u mentioned the vlan info will be updated on the swithces A and B as per switch A.

and ur 8 answer is that u can use vlan maps to prevent communication between the pc's in the same vlan.




Re: interview Question asked to me ...

Switch A server Vlan 3,4

Switch B Client

Switch C Vlan 5

IF revision number of Sw A > Sw C

Sw C will have Vlan3,4

I think you want to say revision number of switch A < Sw C (Not B) as u have added switch C. In this case Switch A will have vlan 5 not 3,4.

Re: interview Question asked to me ...

Interesting job interview questions :). When I'm looking for job, I usually end the interview when the interviewee start asking this kind of Q.

Some of the Q will have different possible answers. It depends what the interviewee think is the right answer.

Re: interview Question asked to me ...

how embrassing when you're asked a basic technical question in interviews and cannot give the correct answer :( and after the interview, you figured out the answer....