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Monday, August 9, 2010

Important C Networks Interview Quesitons

Questions in Brocade R&D

1. explain about function ptr
2. height of the tree
3. order of the tree (types of traversal)
4. tell me about structure padding
5. explain about hash function
6. what is static variable
7. difference between global variable and static variable
8. virtual memory segments
9. Rip convergence time with several topologies
10. what is HA
11. difference between HA and pizzabox stacking
12. differnce between sll and dll
13. average case of quick sort
14. binary search
15. why we need double ptr
16. rope lighting puzzle
17. why ARP?
18. smaphore?
19. diffrence between RIP and OSPF
20. question about DCB
21. question about CN

Infinite Solution (comm net ) Interview Questions

How many Collisions Domains are there in a switch ?
Ans : That is equal to the Number of Ports in the Switch

How many Broadcast Domains are there in a switch ?
Ans : Only One

How can we Increase the Number of Broadcast Domains ? How ?

Ans : yes, Vlans

What is the Upper Limit for the Number of Vlans in a switch ?
Ans:4096 (2 ^ 12 =4096) 12 bits

How RSTP is Different from STP ?

How Distance Vector Routing Differs from Link State Routing ?

Which Converges Faster RIP or OSPF ?

Why PTP when we have NTP ?

Why NTP cant Achieve Nano Second Sync ?

Explain what you know about OSPF ?

Explain a bug you fixed ?

What are the Data structures you Know ?

when will you use typedef ?

how will you copy an array to another ?

Ans : i said MEMCPY , but he said there is one more way ?
i dont know :(

How will you copy Structures ?

use MEMCPY, Assign Individually (if Pointers and Strings are present we have to copy them Individually)
or use assignmnet s1=s2;

what ## operator how it is used in Macros ?

Ans : ?????

How will you find a number is a power of 2 ?

x&(x-1)  ==0

Explain me steps in Reversing a Linked list 2 ptr Approach ?

CISCO interview questions....

1. Conditions for ports to get aggregated.
2. Is the below arithmetic operations allowed on pointers.
int *a, *b, *c;
c= a+b;
c= a-b;
3. Write a pgm to determine the length of a string without using counters.
4. Write a pgm to swap the first and last character of a string.
5. Explain MRP. Use of MVRP.
6. Pkt format. How 4k VLANS get encoded  in MRPPDU .
7.  What are the three most important things done in a switch when a VLAN is configured?
8 . Explain the VLAN path creation and data traffic forwarding using MVRP.
9.  LLDP specific questions.
10. Process creation in linux.
11. How MRP task gets created in ISS.
12. Will LA work over layer 3 ports.
13. Explain woirking of STP. How root bridge and ports are getting selected.
14. PNAC related questions (in fact they asked all the protocols that was written in the resume.)
15. HA related qns. Qns related to the usage of Gracious ARP.
16. What will happen if a malicious user is sending control packets at a high rate to the switch. How to handle such a scenario.
17. Some questions related to CPU performance..
18. What are the different storage classes?
19. Why shld a variable be declared as static. (Need for static variables)
20. Qns on register storage class. When will a variable be declared as register.
21. What will happen if a programer declares the storag type of 100 local variables as register.
2 2. Whats the format of function with variable argument list? Most commonly used function that has variable argument.
2 3. How will the compiler know the number of arguments in a function with variable arguments.
24. Some more questions on variable argument list.
25. Qns on packet flow. Explain the flow that occurs when a packet is received on a port.
2 6. Type of message posting mechanism used.
27. Different data structures that I have used. What is the criteria for choosing a particular data structure.
28. Debugging tools that I have used.
29. What is the approach taken while writting the test plan.
30. Software life cycle model used in the project.
31. How the RTM is prepared.
32. Difference between access port and trunk port.
33. What will happen if one port in a port channel is access port and other is trunk?
3 4. Definition of Hashing.
35. What is hash function?
36. How the collision in Hashing is handled?
37. Some general questions on RB Tree like how it is balanced.
3 8. What will happen if the tree is not balanced.

Brocade interview questions.

Courtesy: Abishek


Requesting Prabu to share his part.

1> Most of the questions were on IGMP protocol (60-70 %) (Data Structure, Interaction with BCM , Timer involved)
2> need of Check Sun in TCP Fiels
3> Need of Check Sum in IP Files
4> Whuch checksum keep on chanfing on differnt hop ?
5> How Learning happens for Tag/Untag Packets
6> How Multicast entry arte programmed in BCM?
7> Differnce in Multicast Table for Mac and IP Based Snooping
8> What is ARP and RARP ?
9> Where is RARP protcol works ?
10> How Routing works ( 3 nodes are there what will packets format at each node ?)

Questions in C
1> What will happen if we call the function recursively ?
2> What is the o/p when two pointers are substracted ?
3> If we are given two pointer p and p+1 can we find out type of poiner ?
4> what is differnce betwwem macro and inline function
5> Define a macro for calculating square
6> O/p of following
char *a= "hello",
a[0] = 'b'
printf ("\r %s \n", a);

7> Differnet Type of Memory (Stack Heap, ...)
8> What are the sequence happen when a function is called ?
9> what haapen when a local variable is returend from the function ?

1> What are pthreads ?
2> Differnce between thread and process ?
3> How OS Schedules differnt threads ?
4> Need of Semaphore in Multi Thread Application ?
5> Differnt element of Process Table
6> Differnce betwwem malloc and calloc

Programs to Write

1> An Array of 20 elements is defined and initialized with 0
Some of them are initilaized to 1 for eg: a[3] =1 , a[7] = 1 a[8] =1 a[9] =1 and a[20] = 1;
Output should be 3,7-9,20

2> Program to Display information from Single Link List in Sorted Order.

Sl. No. Team/Project    Experience (in years)
               Development     SQA
1       SGSN    5 to 10 1 to 5
2       MME/LTE 3 to 5  1 to 5
3       Automation              1 to 5
4       PDSN            1 to 5
5       Diameter        3 to 11 1 to 5
6       In-line Services        4 to 7  1 to 5
7       IMS     1 to 5  1 to 5
8       ASNGW   8 to 12         1 to 5
9       Femto CDMA              1 to 5
10      AAA     1 to 6
11      ICSR    5 to 10
12      TPO     3 to 6
13      Tools   3 to 9







I would be the greatest sinner in the world, if I do not mention about Muthuraj before starting this mail. Had not for Muthu, I would have packed may bags and headed to destination after the first round itself. Hail Muthu for starting this mail chain

{Do curse Prabu for not sharing anything}. ?

O.K. Jokes Apart, I attended interview with Juniper Networks B’lore. I am keeping my fingers crossed for the result (I am hoping for some good news, please do pray for me). It consisted for five rounds of face-to-face interview. Earlier I had done with a round of telephonic and the questions have been shared already in the mail chain. It consisted of all the flavors in the interview, Protocols, C, Pgming, OS (?) & Attitude test. Sure, it was a very nice experience.

1.  First round was more of C basics and Protocols
2.  What is the difference between RSTP and MSTP?
3.  Explain RSTP
4.  Explain MSTP
5.  Draw a topology and explain RSTP
6.  Explain the MAC address table build-up in a network
7.  How does it learn?
8.  What is the difference between switching and Routing? (Hail Chezhian)
9.  Were you involved in any design? I explained PTP (should have chosen something else)
10. Why you chose this?
11. I explained PTP
12. Explain PTP and population of DS
13. How your design is useful in the packet flow?
14. Write a pgm to delete a node in DLL
15. What are the types of vbles?
16. Explain static
17. explain extern
18. why static vble value is never lost?
19. what is life-time and scope for all the variables?
20. and many such
21. Second round was again PB and C
22. What is PB?
23. Explain PB
24. Explain PBB
25. Explain a typical scenario of usage of PB
26. Why we need to use CEP and CNP?
27. What is the need for two different types of Ethertypes?
28. Can we achieve the same without difference ethertypes? (This and other PB, STP related stuff were mere discussion)
29. Write a pgm to do strcpy
30. write a pgm to do strcpy even if addresses overlap (I forgot this)
31. some wrong C code he wrote and he asked to spot the error
32. Stack and heap memory , text, BSS…. Asked everything ?
33. Then the third round. This time it was simple
34. Pgm to delete a node in doubly Olar linked list (need 2 take care of boundary conditions)
35. Pgm to do in-order Tree without usage of recursion
36. pgm to find whether number is power of 2 or not? (only one bit will be set)
37. And other logical questions
38. What you learnt in support? (I told soft skills and he was happy)
39. Finally he told HR will meet me (naan kooda mudichutangalaonu nimbi okkanthdu irundhaen)
40. now started the anti climax
41. One more fellow came and blasted everything in OS. I told him I am not that well in OS and am trying to learn.
42. Asked how 2 processes communicate. I told abt shared memory and message queues.
43. Then pgm to find a loop in SLL. I did not do well for this one
44. Pgm to find strcmp
45. Then more questions on C and other OS related stuff.
46. How does sizeof work? ( I said don’t know, he asked me to guess. Then I told probably, this is fn, it declares an instance of vble inside provided as input and finds the amt of memory occupied… reaction was “Out-of-box”. “Idharku thanae asaipattai Balakumara ?]
47. Then final rnd. This was more of Attitude determining round
48. How wuld u test ATM
49. What are the features u like to have in ATM
50. Postman Problem (Just they determine the attitude)
51. Red balls, white balls story
52. Then he explained what the BU is about and what they are doing and abt the growth of their BU. He also told about the protocols to be developed in the coming years.
53. Sari, anadhu ayipochunu nannum 2 questions kaetaen ?




Some more questions for Juniper ?

1.  Explain your current project
2.  How do you handle packet processing?
3.  What kind of mech is used b/w various threads in the project?
4.  What is a binary tree?
5.  What is a RBTree?
6.  Explain RBTree Traversal Algorithm
7.  Explain Tree Balancing
8.  What is Spanning Tree
9.  Explain overview of MSTP
10. Explain various timers in MSTP
11. Can timers be optimized in MSTP
12. Is MSTP implementation resource efficient with all these timers?
13. What is VSTP?==> The Answer VLAN Spanning Tree Protocol.. and is equivalent to PVRST. I did not know this ? shame on me
14. Explain the data structure implementation in current proj
15. Why you choose this one?
16. Any performance parameters considered?
17. Explain the difference b/w MACROs & inline functions
18. What are the storage classes in C?
19. Explain what is meant by "extern"?
20. What does the compiler do when it sees something as extern?
21. How can u achieve the functionality of extern without using it?
22. What is meant by 'static'?
23. what does the compiler do when it sees something as 'static'
24. More questions on malloc
25. what is stack memory and what is heap memory
26. Roughly draw the stack for a function
27. And more questions in C. I forgot
I forgot to attach the questions that asked by Huawei.
Please find thye below.

1. write a function to find the ethernet packet is IP packet or not?
2. write a pgm to find the little endifan and big endian.
3. write a program to convert the HTONL, NTOHL, NTOHS and HTONS.
4. write a program to multiply n with 32? This is one mokkai question?
5. Tell about the VLAN tag format.
6. Draw the ethernet packet?

Today I have attended the force 10 networks interview.
These are the questions asked by them.

1. Delete a node in the double linked lidt.
2. Reverse a linked list. - I used rescursive fun to delete.
3. How to find a given number is multiple of 2 without using shift operator, div and mod operator.
4. Asked questions on GARP.
5. At what base we are choosing the data structure.
6. How many number of nodes in level L. Write a generic formula to find it.
7. One puzzle.

I have completed 5 face to face interview of Juniper. Here are the questions asked to me.
I hope this will helpful for attending the Juniper.

Totally i had 7 rounds of Interview. This is the marathon interview i faced first in my life. But it was very interesting, enjoyable and lead you to learn lot of things.

First 2 rounds are telephonic, questions are

Round 1) Basic C concepts like storage classes, malloc related questions.
Round 2) Whatever we specified in our resume.

Round 3 - Round 7 (Face to Face)

These rounds can be a mixed of C, Data structures and OS.
1. Program to find the little endian or Big endian.
2. Multiplication using bitwise operators.
3. RB tree traversal.
4. Delete a node from double linked list. Should take care of all boundary conditions.
5. Consider you are having the SLL of data 1,3,5 and you are having the new node as 2. We have insert the node 2 in between the 1 and 3 but you have given the pointer of node 3. possible or not?
6. Set the nth bit program.
7. what is the difference between the MACROs and functions.
8. Advantage and disadvantage of MACROs.

1. Postman problem. write the strategy to deliver the mails faster.
2. Ratio of red marbles and white marbles in red box and white box.

Subject: RE: Juniper interview questions

My Experience

1 ) Void function1 (int x)
int couter = 0;

   counter ++;
   x = x & (x-1);

/* What this piece of code is doing */

2 ) Reverse a Linked List
--> i fillowed 3 pointer Approach
---> why are you using Three Pointers ?

3) Linked List Problem , The Interviwer Created his own Problem
--> For solving the problem i need to use Circular linked lists
---> using malloc

4) Three Puzzles

5) I am getting a vlan 100 tagged packet in my switch , explain step by stepwhat will happen ?

6) about PTP (IEEE 1588)

7) About PTP (IEEE 1588) State machine

8)  RSTP , MSTP , STP what do you know abt these protocols

9)  Explain Project in your Resume

10) Tell me abt yourself



I forgot to attach the questions that asked by Huawei.
Please find thye below.

1. write a function to find the ethernet packet is IP packet or not?
2. write a pgm to find the little endifan and big endian.
3. write a program to convert the HTONL, NTOHL, NTOHS and HTONS.
4. write a program to multiply n with 32? This is one mokkai question?
5. Tell about the VLAN tag format.
6. Draw the ethernet packet?

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