Cisco

Cisco came to our college for an SDE Intern opportunity, and it was one of the companies I was particularly interested in because of the kind of work Cisco does around networking and software. Since it was an on-campus process, quite a few students were preparing for it, and I started revising both DSA and core CS subjects before the assessment. The first stage was the online assessment. The test had a combination of coding and aptitude/technical questions. The technical part covered areas such as Computer Networks, Operating Systems, DBMS, programming fundamentals and general computer science concepts. The coding section was more challenging than the MCQs. The questions were based on DSA, and the time constraint meant that I had to quickly understand the problem and decide whether the approach I had in mind would be efficient enough. I was reasonably comfortable with the MCQ section because I had already revised OS and networking basics. However, the coding questions took more time than I expected. I was able to work through the problems, but I wasn't completely satisfied with my performance. After the assessment, I was shortlisted for the technical interview. The technical interview was conducted online and lasted around 45–60 minutes. Cisco's campus interviews can vary depending on the hiring cycle, but public on-campus reports have included questions on IP addressing, OSI and TCP/IP models, networking devices, DNS/DHCP, programming and projects. One 2024 campus report specifically describes a 45–60 minute technical interview followed by project discussion, with the candidate ultimately not moving to the HR round. The interview started with the usual introduction. I gave a short overview of my background, interests and the projects I had worked on. The interviewer then moved to my resume. This was probably one of the most important parts of the round. Instead of spending the entire interview on random technical questions, the interviewer picked things from my resume and started asking follow-up questions. I had to explain one of my projects in detail, including the problem it solved, the technologies I used and how the different components worked together. The interviewer then started testing whether I actually understood the technologies I had mentioned. Whenever I gave an answer, there was usually another question based on it. This made the project discussion more technical than I initially expected. After the project discussion, the interview moved towards Computer Networks. Since Cisco is heavily associated with networking, I had expected this area to be important. I was asked about the OSI model and the TCP/IP model. I had to explain the different layers and the purpose of each layer. There were also questions around how data moves through the layers and why the two models are different. The interviewer also asked about networking devices. I had to explain the difference between a hub, switch and router and when each one would be used. DNS and DHCP were also discussed. I was asked what each protocol does and how they are used in a practical network. One question involved IP addresses and subnetting. I was given a network-related scenario and asked to work out the different types of IP addresses and explain the reasoning. This was manageable, but I realized that knowing the definitions wasn't enough. I needed to be comfortable doing the calculations quickly as well. The networking section was probably the part that made the interview feel different from a typical SDE interview. In most software interviews I had prepared mainly around DSA, but here networking fundamentals were equally important. This is also consistent with other Cisco campus reports. A recent on-campus Cisco SDE internship process included questions from Computer Networks, OS and DBMS along with DSA and resume discussion. Another campus report had a technical quiz covering data structures, algorithms, networking and computer fundamentals. After networking, the interviewer moved towards Operating Systems. The questions were mostly around fundamentals. I was asked about processes and threads and some basic OS concepts. The interviewer also connected a few questions to networking, including how the operating system interacts with the network interface card. There were also questions about file systems. I had to explain the difference between logical and physical file systems and discuss different types of operating systems. I was comfortable with some of these questions, but there were a few follow-ups where I had to think for a while before answering. The interviewer then moved towards DSA. The coding question was not extremely difficult compared with the problems I usually practiced, but the interview setting made it more challenging. I was asked to explain my approach before writing the code. The interviewer wanted to understand the reasoning behind the solution and the expected time complexity. I first discussed a straightforward approach and then tried to improve it. One thing I noticed was that the interviewer wasn't just checking whether I could write syntactically correct code. I had to explain why my data structure was appropriate and what would happen for edge cases. I was able to make progress on the problem, but I wasn't as quick as I wanted to be. I also spent some time thinking about optimization, which reduced the amount of time available for the remaining questions. After DSA, there were some DBMS questions. These were fairly basic compared with the networking discussion but still required clear fundamentals. Questions around databases, SQL and the difference between relational and non-relational databases came up. I was also asked about concepts that I had studied as part of my core CS subjects. The interviewer then returned to my projects for a few more questions. This time, the questions were more practical. I was asked what I would change in my project if the number of users increased and how I would handle certain technical limitations. I tried to explain the decisions I had made while building the project and what I would improve if I were given more time. The overall interview was conversational, and the interviewer was helpful whenever I got stuck. However, the questions moved fairly quickly between different subjects. I had to switch from networking to OS, then DSA, then DBMS and back to projects. That was probably the biggest challenge for me. I had prepared these subjects individually, but I hadn't practiced switching between them during a single interview. Towards the end, the interviewer asked if I had any questions about Cisco or the internship. I asked about the kind of work interns usually get to do and the technologies used by the team. The interview ended on a fairly normal note, so I wasn't sure about the result immediately afterwards. A few days later, the results were communicated, and I wasn't selected for the next stage. In this hiring cycle, I didn't make it to the HR round. I wasn't too disappointed with the interview itself because it showed me exactly where my preparation needed improvement. My DSA preparation was decent, but the Cisco interview made it clear that for a networking-focused company, Computer Networks cannot be treated as just another subject to revise before placements. The biggest takeaway for me was the importance of core CS fundamentals. I had initially expected the interview to be mostly DSA and projects, but networking and operating systems took a significant part of the discussion. I also realized that resume preparation matters a lot. The interviewer can take any project or technology from the resume and ask several follow-up questions. So it's better to have fewer projects that you understand properly than to mention technologies that you can't explain. After the interview, I went back and revised Computer Networks more seriously. I focused on the OSI and TCP/IP models, TCP vs UDP, DNS, DHCP, HTTP/HTTPS, routing, switching, IP addressing and subnetting. I also revised OS and DBMS fundamentals and continued practicing DSA. For future Cisco interviews, I would prepare in three parallel areas: DSA, networking and projects. I would also revise OS and DBMS because they can easily appear as follow-up questions. Overall, the Cisco SDE Intern process was a useful experience even though I wasn't selected. The interview wasn't based on one extremely difficult coding problem. The bigger challenge was having a broad understanding of software fundamentals and being able to explain them clearly under interview pressure. It also changed the way I prepared for subsequent interviews. Instead of assuming that every SDE interview would mainly revolve around DSA, I started giving more attention to core CS subjects and making sure I could confidently explain everything written on my resume.