I applied online. Got an email to schedule phone interview the very next day. Phone interview was mostly focused on C, OS and Networking. Since I did well on that, I was called onsite after a couple of weeks. Onsite consisted on 5 tech rounds and 1 HR round. Tech rounds are entirely focused on C, OS, problem solving skills and your resume. The interview process was very smooth and candidates were well taken care of. I am waiting to hear back from them.
Tech questions were as follows.
1. Programs for binary search, linked list node deletion, string reversal, calculate no of bits in a number in given base, division of floating point numbers.
2. Difference between macros and functions, why/where to use macros
3. Use of static
4. Scheduling
5. How to prevent deadlocks
6. What data structures is used in routers
Overall, the key is to be thorough with C, OS and memory management