Sandvine Interview Experience | On Campus FTE 2021 for Networking Software Developer

Sandvine Technologies visited our campus on September 19th, 2020. The whole process was virtual since this was done in the covid era.

First Round – Online Test: The test was conducted on HirePro platform. The online test consisted of 3 sections. Each were to be done separately, and were even timed separately. We cannot navigate to another section before completing the current section. 

The first section consisted of basic aptitude questions, 15 questions to be done in 20 minutes.

The second section consisted of technical questions related to CS subjects like OS, DBMS, CO, CN and output questions from various languages like C, C++, Java, Python. 20 questions were to be done in 40 minutes. Initially it felt like there was a lot of time for this round but I had to scamper around in the end.

The third section was the coding section. Interestingly, we needed to write the code in text editor and not pass test cases by writing it on some IDE. There were 4 questions in this. I did all of them.

1. Given a matrix. Find the difference between the maximum sum and minimum sum that can be obtained by traversing through a straight line in the matrix (either horizontal, vertical or diagonal). 

2. Given two trees T1 and T2, find whether T2 is a subtree of T1 or not. ( https://www.geeksforgeeks.org/check-if-a-binary-tree-is-subtree-of-another-binary-tree/ ).

3. Given a string that contains a list of words. Find the words whose length is closest to the average length of all the words provided. Eg: Given string – “Sachin Tendulkar is my favorite batsman”. Avg word length = 35/6 = 5.83 Closest words – {“Sachin”} (it has 6 words, closest to 5.83). Remember, we needed to find all such words.

4. Reversing a doubly linked list – the question was a bit twisted but this is what it wanted.

5 students were selected for the interview from around 200 candidates.

Interview Round – 1(Technical): They took only one round of interview. The interview was conducted on Zoom . My interview was slotted at 2PM, and I was the first to be interviewed. There were 4 panelists. It started with my introduction. They started with my current ongoing project – which I had not done much of (and not even mentioned in resume). It was a machine learning project – so they tried to ask about how I would go on about, my design of the model and all that. I told them I am just at the data collection phase since data for my project is not readily available and I have been searching for quite a while now, also this was the first time I will be working on speech data, so I had no design plan in my mind as of yet. I told them since data will be scarcely available, I might need to opt for machine learning methods rather than deep learning. From there, they asked me the difference between machine learning and deep learning, also asked me about CNN, which I explained. Then, I had a project on networking, where I worked on TCP. So, some standard questions on TCP were asked. After that, a panelist asked me about congestion, and why it happens. I explained in detail. Then, he asked how will you detect congestion, told him about 3 duplicate acknowledgements and timeout. Then he asked me how will I handle congestion, I thought of various ways but went with the simplest mechanism of slow start phase and congestion avoidance phase. Then he directly asked me about ECN. I had read about explicit congestion notification in previous semester, and remembered some important points from there. I gave a very detailed explanation about how ECN works. I also told them that ECN is not yet implemented on our day to day network, to which he contradicted that ECN has been out for long. I again contradicted him by telling that ECN has a flaw (which I had forgotten) because of which this beautiful mechanism is not implemented in our day to day TCP protocols, however DCTCP kind of works in an isolated environment, so it implements ECN. I also cited lots of sources for my information and also told them about the current protocols in research which use modified versions of ECN. Basically, I talked about ECN a lot to prove my point. Then, he gave a code and asked if it work properly. It had a void pointer and a void variable. I told him it won’t work because of that void variable, void pointer was no problem. Then he asked me a bit about data segments, static variables, etc. After that, he asked me how I would store records indexed on phone numbers, I gave him multiple mechanisms for that. Then they ended the interview. I asked them for a feedback, and also how a normal day at Sandvine looks like.

Finally, they selected only one candidate. I was finally selected in my 8th interview.

Try to be prepared beforehand for the placement season, GeeksforGeeks will be your biggest messiah. You might need to refer to other resources as well like maybe GATE notes or Ravindrababu Ravula videos for OS, CN, DBMS, some HR questions, aptitude from Indiabix(if needed). Also, research about the company before attending its interview. I think your seniors or peers would have provided you other advises.