One phone session followed by 5 sessions of 1-1 interviews. HR was all praises on how good F5 is but I found it quite otherwise. We discussed salaries and F5 pays well. Technology is good, but they have some old timers who are trying to protect their turf. The office location is decent, but the buildings shake when trains pass through. 2/5 Interviewers were very well prepared and had specific questions related to position and work at the team. Even though I did not nail all the questions, I enjoyed the discussions and the problem solving mode they worked in. DNS, HTTP, TCP/IP, C++, Security, Data Structures. 1/5 interviewer asked very open ended general questions. I caught him yawning, before lunch. 2/5 interviewers were not well prepared and to a certain extent were hostile, aggressive and offensive. Both were older. One was very knowledgeable but arrogant. It was difficult to understand whether this person was asking a question or just giving an opinion for me to comment on. Twice, the other interviewer hinted that I was lying about how I executed on a problem and project. Did not provide any supporting evidence for me to counter. I tried to defend myself but this one nodded, waved and moved on, making notes and letting me know who was in control and who was being judged. This nasty behavior put me off for the rest of my time at F5. My own assessment after the interviews was that I did good technically at 3/5 interviews and ok at 1/5 but this team will not be a good cultural fit.