One of the toughest interview processes I've ever experienced. The people in there really know what they are asking and will crush you if you try to fool them. They will, literally, extract every drop of your knowledge. Don't even think about mentioning a protocol or system characteristic which you don't truly grasp all the intrinsic details - they will ask more and more about it.

A few questions about operating systems, but no kernel-internals questions like Google/Facebook. The main focuses are on networking and security (never forget they are a bank). Know the OSI model inside out. Some questions start at the application layer (7) and go all the way to the physical layer (1). Know TCP, UDP, DNS, HTTP, SSH and specially TLS and VPN. Many questions on reliable and secure ways of transferring data. Knowing the handshake details for both TLS 1.2 and 1.3, specially their differences what is SNI/encrypted-SNI, is the least expected. Other security questions like symmetric and asymmetric private/public key cryptography.

The whole process will look like:

1. Recruiter/HR interview
2. Take-home test (72h deadline, 4-8h work time)
3. Two rounds of technical interviews
4. Engineering Lead interview

How does your computer gets IP/netmask/gateway information when connected to a network? Explain the DHCP protocol. Describe each of the DORA stages. Which is the source IP on the packet that goes in the "Discovery" phase?