first round (manager round )- they ask for your work, your team strength, technology on which you work. why you want to change.
they says they received 4000+ alerts in a day and those needs to be looked upon. try to see your reaction (it looks the product is not stable)
2nd round (Senior manager round)- same like above. check your language, reaction, behavior etc.
3rd round - BU head - this guy will ask all and everything in details even beyond your current job profile. ask more about management question like (what are the KPI's, how will you show performance of your team to management - he don't get satisfy if you will tell him in detail, he has answer set in his mind and expect that only). where you will see to yourself in 3-5 years. here again he expect what he has in his mind what ever you will see he will do cross question.
he basically looking for a guy with all expertise but don't want to give the handsome salary.