questions on work experience and take home custom exercise building a web app using APIs that they ask you to change during technical interview theoretical questions about design, system architecture

online zoom meeting straight forward. Just did research about the company online and got tthrough the interview fine. Barracuda Networks is a leading provider of cybersecurity solutions, specializing in email security, network and application security, data protection, and cloud security.

According to the process their are 2 technical round and then manager/HR discussion I got this opportunity via recruiter, i got first call where they asked some basics details like your current role, notice period, salary expected, years of experience. then again i got a phone call to test my basic linux knowledge. after few days my first technical interview was scheduled, he first introduce himself and explained about the company then everyone's favourite question " tell me about yourself" in that i mentioned my past intership and current role, and got some related questions on experience. i was giving interview for the role of c++ developer but they were expecting C developer still i had some knowledge so i told will try to answer he asked few questions related to structures, memory, pointers, and one coding question related to bit manipulation things went wrong when he mentioned about multi threading programming, synchronisation and topic related to it as i dint haveany programming knowledge so was not able to answer. later he gave a feedback, saying i did very well in c++ and most of the questions but they are looking for someone with multi threading programming and in C, but what was wrong is they didn't mention this in JD and according to JD they were fine with C/C++, python, java and in interview only C and also no mention about multi threading as i hace seen many JD if they want someone with that knowledge then they will clearly mention. at least i would have prepared.