I was approached by recruiter. There's a phone interview with general discussion (introduction, goals, why, etc.) of about 20-30 minutes followed by a short list of entry level technical questions (how many addresses are in a /27 network, what command you use for updating initrd, which file you modify for service X, etc).
After that there was a second phone interview which lasted 40-45 minutes and was focused on coding (questions below).
They're not hard but require focus and combination of different skills.