Systems Engineer Interview Questions | Glassdoor

# Systems Engineer Interview Questions

Systems engineers work closely with systems analysts to maintain a company's IT system by developing the operating systems that run computers. Expect to be quizzed on a variety of technical questions that will test your knowledge of how computer systems work. Employers prefer candidates with a bachelor's degree in an engineering field and previous experience with technology.

## Top Interview Questions

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Jun 7, 2010

### Senior Systems Engineer at Qualcomm was asked...

Apr 25, 2012
 Given a wireless channel with loss rate 0.1, what's the throughput one can get with retransmission. 8 Answers It can modeled as binary symmetric channel. As to my understanding, channel capacity can be acheived with perfect feedback and simple retransmission scheme, so i guess the answer is 1-H(0.1). 10/(1.23456...)=8.1 packets per sec Interviewer was correct. With probability 0.1 you have one retransmission, with probability (0.1)^2 you have two, etc., since you can also lose the retransmitted packets, reducing the throughput to approximately 0.89. Show More Responses It is equivalent to simply a binary erasure channel with erasure probability 0.1, whose capacity is 1-0.1 = 0.9. aa should re-learn information theory and stochastic process First of all I don't think it has anything to do with the capacity of BSC. Note that h(0.1) = 0.46 and that means 1 - h(0.1) is roughly 0.5. If the packet error rate is 10% then BER is in the order of 0.1 / N where N is the length of the packet in bits. For that, the capacity of BSC is almost 1. In any case, in the non-ergodic case I believe the throughput is less than 0.9. Assume you want to send packets p_1, p_2, ..., p_k and each one takes N_1, N_2, ..., N_k time slots. Then, define the k-Packet Throughput (I made it up) as follows k-packet Throughput = (k / (N_1 + N_2 + ... + N_k)). Note that this throughput is a random variable. We can define the throughput based on this as the expected value of k-packet Throughput with respect to random variables N_1 , N_2, ... E[k-packet throughput] = E[ k / (N_1 + N_2 + ... +N_k)] 8' from the law of large numbers we have N_1 + N_2 + ... + N_k -> k E[N] = 1 / 0.9 * k. This suggests that k-packet throughput is a random variable which converges to its mean for large k, but for a finite k, its average is less than 0.9 All in all, I would have answered the question the way you did. In the long run, out of N transmissions you have 0.9 received and therefore the throughput should be 0.9 Model the problem based on the average number of transmissions it takes to deliver a packet. Let N be the number of transmissions. Then: Pr[N=1] = 0.9 Pr[N=2] = 0.1*0.9 Pr[N=3] = 0.1*0.1*0.9 ... and so on. The expected number of transmissions per packet is: E[N] = Sum{ k*Pr[N=k] } = 1*Pr[N=1] + 2*Pr[N=2] + 3*Pr[N=3] + ... where the summation index k goes from 1 to infinity. Then the throughput is 1/E[N] packets per transmission, which is 0.896... In the last solution, the number is calculated incorrectly. Accurate calculation gives the expected number of transmissions per packet E[N] = 1.11111, so that 1/E(N)=0.9, which corresponds to the reduction of transmission rate by exactly 10%, as suggested earlier. p=0.1 - probability of a packet transmission failure If we transmit a sequence of N packets with retransmission then an expected number of successfully transmitted packets will be E[N]=p*E[N-1]+(1-p)*(E[N-1]+1)=(1-p)+E[N-1], and as E[0]=0 it easy to solve the recursion: E[N]=N*(1-p) Expected number of successfully transmitted packets per one transmitted packet will be C[N]=E[N]/N=(1-p). The channel capacity is limit of C[N] as N approaching to infinity that is clearly equal to 1-p=0.9

### Systems Engineer at Pure Storage was asked...

Dec 5, 2013
 Technical questions were relevant to the position I was applying for, and I felt they were straight forward enough. I think there was a great focus on why I wanted to work here, and how I felt the culture would fit me and vice versa. 3 Answers One word - enthusiasm. Pure Storage is very proud of the product and culture they have created, and they are looking for people who are excited to join the team looks like an review by the company HR nope... it's me (http://www.linkedin.com/pub/james-fisher/2/124/4aa)

### Systems Engineer at NVIDIA was asked...

Jan 28, 2013
 You are driving on a racetrack. The first lap you averaged 60mph. How fast do you have to drive on the second lap to average 120mph on both laps? 4 Answers 180mph The correct answer is that it is not possible to average 120 mph for both laps, unless you can go infinitely fast and complete the second lap in zero time. In order to average the speed of 120mph for two laps, time needed is (2/120)=1/60h. first lap avg. speed is 60mph so time taken is 1/60h. so it took 1/60h to complete one lap. hence time left to average speed id (2/120 - 1/60h = 0. therefore we cannot average the two laps speed unless second car is infinite fast to cover the lap in 0h. Show More Responses Without knowing details, lets assume the track is 60 miles long and the car covered it in 1h, at the average speed 60 mph. In the second lap, the car needs to cover another 60 miles, so total 120 miles. In order for the overall average speed to be 120 mph, the total distance has to be covered in 1h, so the second lap has to be covered in 0 time, which is not possible unless we travel and infinite speed.

### Senior Systems Engineer at Yahoo was asked...

Feb 17, 2013
 If you could be any Linux command, which would you be? 3 Answers "whomai" :) Was excited - correct one - "whoami" top sleep

### Systems Engineer (Field) at Eze Castle Integration was asked...

Feb 17, 2010
 name the 5 FSMO roles 2 Answers i named 4 of them missed Schema LOL Domain Naming Master, Schema Master (the two forest-wide ones), then PDC Emulator, Infrastructure Master, and RID Master (the last three are one-per-domain roles...)

### Systems Engineer at Apple was asked...

Aug 25, 2009
 How can you edit/change the file which has only read permission 4 Answers You just need to resave with a different name If you are the owner, you can save your changes regardless. In vi, do a w! . The administrator can do it. So check you are as the good one to edit the file. Show More Responses chmod 755

### Associate Systems Engineer at Space Systems/Loral was asked...

Feb 1, 2011
 What do you think is in a satellite? 2 Answers Actually satellite is clearly defined. It is any object that orbits a planetary object. This includes moons or other natural satellites. solar panels, power converters, etc. (Use your imagination.)

### Electronics Systems Engineer at Cummins was asked...

Jun 8, 2012
 Situational Questions, Resume and preparation with examples is the key 2 Answers I fully prepared. I made like 100 questions and answers. Everything was covered in that. Actually, I didn't have any difficult questions as such. Hi. I wanted to know if they mentioned you the team they're interviewing for?

Dec 5, 2013