Cisco Interview | Experience : 2+ years


I applied through Cisco Career and received a call from the HR in a week or two. I had three technical interview rounds.

Round 1 (Telephonic/WebEx)
The first round started with me explaining in very brief about my experience in the networking domain which followed with the following questions:
1. Flow of packet in Linux kernel
2. Virtual Memory/Paging/kernel space/Userspace
3. Stages of C program compilation
4. Design a client server model over TCP protocol
5. Indirect question related to memory layout of c program(stack, heap, data segment)
6. Indirect storage classes in C(Code Output)
7. C concepts on Static, global variable & static function

Round 2 (Telepresence)
1. structure Padding/Uses/how to tell compiler not to pad a structure/when it is needed?
2. Double/Single Linklist reversal
3. Last nth element from a linklist
4. What the compiler does when we define a variable volatile in architecture level ie. what happens with cache, primary memory etc?
5. Little and Big Endian. How a system will verify weather its in little or big endian?How to write endian free code? hint: htonl
6. Program to Detect loop in a circular linked list.
7. How kernel handles interrupt latency when there is a high frequency of interrupt?
9. What different types of IPC mechanism you have used? What you think the fastest IPC mechanism? Why?

After that some discussion on pointer in C, data structures, multi-threading and locking mechanisms.

Round 3 (Telepresence)
This round was a detailed discussion on stuffs I have worked on in previous company, which includes NAT, Fragmention(IPv4/Iv6), Linux Kernel, Driver development etc. All discussion began with very simple question like What is Fragmantaion and then slowly going to depth of the work I did like the infrastructure of the module, Data structures I used, various callback implementation, various issue he thought that might have, how I protected data corruption by properly locking the module yet not loosing any performance.



A week later I got call from the HR with an offer.

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