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After reading all the GATE success stories here, I can't believe I am writing this today for ISRO. TL;DR.

Hello Everyone! My name is Mamta Satywali, I am Computer Science Graduate(2016) from G. B. Pant Govt. Engineering College, New Delhi. I secured AIR-1 in ISRO Scientist-2018. It didn't come the easy way for me because in GATE-2018 I was able to secure an insignificant AIR-3381. I was depressed. Yes! Panic Attacks in the exam are real(for me, panic attack was just an excuse people use, before GATE-2018 happened to me). For a person who was getting Rank-20 in test series just 3 days prior to the GATE Exam, there is no way to not believe the same.

I left my job in Sopra Steria as Software Engineer in mid-August-2017 to pursue higher studies in old IITs only. Let me be very honest here, I didn't know about ISRO's recruitment process last year at this time, which makes it clear that my goal was always GATE only. GATE is the only key to get success in ISRO. ISRO⊂GATE, as we all know.


After turning all the google search links purple for GATE CSE preparation(while I was serving my notice period), I decided not to go for coaching. I had two prime reasons[this depends entirely on you]-

1. I had already paid a bond amount of Rs-1,00,000 to Sopra Steria so, it was not easy for me to spend another Rs-80,000 for coaching.

2. I had notes of AIR-101 of GATE-17. Yes! Akash Sheoran was my biggest inspiration and helping hand in this entire journey because I had never faced GATE before. His notes helped a lot to keep track of what and how topics should be studied.

What surprised me the most is that no one promotes NPTEL lectures except obviously GateOverflow. Yes, they are slow but they are the real gems, use 2X speed and you would love to learn from them. I did my "entire preparation of almost every subject" from NPTEL lectures with reference books as and when required. I had to spend some time to gather the best ones but it was worth in the end. I request each aspirant, please don't underestimate NPTEL videos if you have less time to prepare.

July-August: I was done with Engineering Maths and DLD.

September-November: With the speed of approx. three subjects per month, I completed the rest of the eight subjects. I prepared them in the same sequence as given in the official GATE Syllabus for CSE. I used to solve all GATE previous year questions as soon as I completed a particular subject.

Don't forget to revise completed subjects while you are studying a specific subject especially Engineering Maths. I did this mistake which cost me my entire December for revision only.

January- Full-length Test Series of GO, GATEBOOK, MADEEASY.

04-02-2018- Spoiled GATE Exam.

Mistakes which I did and you should not-

  1. Not revising at periodic intervals. 
  2. Didn't solve GO PDF, I used Made Easy's Previous year question book.
  3. Attempting test series late, hence less practice.

After GATE, BARC backstabbed too, but for BARC I completed GO PDF once.

April-2018: Solved GO PDF again for subjects that have good weight in ISRO like Programming & DS, Algo, CN, COA, OS, TOC and DB. Solved ISRO's previous year(2013-2017) paper with time constraints(90 mins).

22-04-2018(ISRO Written Exam)- I had a really bad throat that day. I did go out of class for 10-12 mins during examination because I was disturbing others with my cough and all. So, with my low-confidence and less time in hand, I came back and solved paper calmly whatever may be the result. No panic attack here because I thought I have already lost the battle.

22-06-2018(Written Result declared)- I secured AIR-96 in written test with 129 marks out of 234.

13-07-2018- Interview Schedule was out.

I read all interview experiences available online and penned down each and every question asked so far in all interviews in my notebook. I asked Sandeep for guidance. A Big thanks to him because his advice did wonders for me, my interview was more or less the same as he guided.

Interview Experience-

Date of interview- 30-07-2018 

Venue- DOS Staff Housing, Antariksh Vihar, DWARKA, New Delhi.

Time- 8:00 AM.

In the big reception hall, everyone was asked to sit and wait for their turn. At appx. 9:00 AM, I was asked to go upstairs for document verification. Document verification was done. I waited till 1:00 PM for my interview turn. This time they had no female priority, we were called up in the same order as given in Interview Schedule. The Interview happened on the 3rd floor.
In the interview panel, there were appx. 10 Scientists(I1, I2,...I10) and Chairman(Mr C) at the centre. I1 asked me to sit at a distant chair facing chairman. I greeted everyone and then I was asked to introduce myself.


Mr C- So, What was the organisation you worked for?
Me- Sopra Steria.
Mr C- What did you do there?
Me- Told my clients name and my work. They were not that much impressed.
Mr C- So, What was your major project in B Tech?
Me- Image encryption using Cryptography and Steganography.

Mr C points I1 to ask questions.
I1- What is the difference between Cryptography and Steganography?
I ended up defining them but not in bookish language.
He reiterated that I asked for the difference.
To which I answered better and Sir was convinced.
I1- So, What did you use for encrypting images?
Me- Playfair encryption.
I1- Why?
Told the reason.
I1- What kind of cryptography it is?
Me- Symmetric.
I1- Why not others?
Me- It takes more time with Asymmetric ones.
I1- Name one asymmetric?
Me- RSA.
I1- What makes RSA special?
I2- Explain RSA on board, how it works?
I2- How would you send a secret message to me using RSA?
Explained. They all were quite impressed.
I1- So, Which algorithm did you choose for key sharing?
Me- Diffie Hellman.
I2- What is Diffie hellman's limitation?
I2-Do you know Elliptic curve Diffie?
Me- No.
I1- You have worked in website development. So, What is the encryption used in "s" of https?
Me- I don't know.
I1- Do you know any Hashing Algorithm?
I1-What was the limitation of MD5?
I3- What are your fav subjects?
Me- DS, Algo, CN, OS.

I1- Okay! Now some Rapid fire questions. What does a linker do? [They expect one-word answers here.]
Me- Answered.
I1- I have a 6 character password of alphabets in uppercase, how many brute force combinations are there?
Me- 26 to the power 6. [This should be 2 to the power 48, though.]
I1- What is the scope of a variable?
I1- What does static or global variable do?
I1- What is a write-back cache?
I1- How would you define binary trees?
Me- Doubly linked list.
I1- How would you implement it, the data structures?
Me- Using Struct having union inside to avoid extra space for dummy nodes.

Mr C asked others to question-
I4- I have 220 as a number, how many bytes in binary representation do I need and how many in ASCII?
I4- Do you know Quantum encryption?
Me- Ma'am, I have heard about this but I am unable to recollect.
I4- No worries. [She started with another question.]
Me- I am sorry to interrupt. I know what is Quantum Encryption. [Starts explaining Quantum encryption, I4  & I1 smile on my curiosity and stopped me midway saying we know that you know it.]
I5- So, when is a binary search tree used?
I5- What Data Structure do we use in recursion?
I7- Difference between void and null?
I7- Difference between a full binary tree and a complete binary tree?
I4- What formats did you use in your project?
Me- I didn't get the question, Ma'am.
I3- She is talking about the format of input data.
Me- I didn't get it, I extracted pixels from images...[Interuppted]
I3- No the formats of images like png etc.
Me- It was implemented for png and jpeg using RGBA.
I6- Which is the fastest sort?
Answered with reasoning.
I6- How many trees do you have with 3 nodes, draw on board?
Drew all 5.
I8- So what is the processor in your computer?
I said Windows. [The side effect of reading interview experiences multiple times is you think, you know what they want to ask and don't listen to the question presently asked.]
They all laughed and said Oh! you have Windows as a processor.
Me- I am sorry that's OS and processor is i5.
All- Thank you, Mamta.
As I was moving towards the door. I1 stopped me and asked for my score in the written test. I don't know why that was asked. Overall, the Interview Board was very supportive, it didn't feel like an Interview at all. Duration of the interview was 20mins.

Interview Preparation-

  1. I prepared each and everything related to my Major Project which is the only reason I chose Computer Networks as my fav subjects for this interview.
  2. I solved GO PDF for DS, Algorithms, OS which was on my fav's list.
  3. I had job experience so I also did basic level preparation of topics related to the projects I did.
  4. Most importantly, you should prepare Software Engineering. I wasn't asked questions from it but this subject if asked may lead you in the danger zone if not prepared.
  5. A day before the interview I tried to answer each question from each interview experience which I already jotted down in my notebook. Just to gain some confidence.

Last but not the least, I am still a GATE aspirant, I am yet to achieve my goal in GATE. So, please make your own strategy, this worked for me in ISRO, this might not work for you. I have just put in extra efforts for ISRO as it was my last hope of this year. I dedicate my AIR-1 entirely to GOD and my family's blessings. Special mention for Sukannya, she was the girl who believed in me even when I was unable to believe myself. Thank you so much GO for gifting me such a great friend!

I suppose, the number of times I have used the word "GO PDF" above, I don't have to describe explicitly the importance of GateOverflow! 

Thank you so much for reading! 

posted Aug 27 in Interview Experience by Active (2,315 points) | 4,645 views


Congratulations, i learned so many things from you.
Congrats Mamta, anyways I too spoiled Gate 2018!
Amazing! Congratulation !!
Thank you so much @Lakshman, @vishalshrm539, @cool_dude :)
@Mamta, How many marks you got in the interview ? please share if you don't mind...
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