Northrop Grumman Senior Software Engineer interview questions

Contacted by a Northrop Grumman recruiter and scheduled for a phone interview. Then was invited for an on site interview.

Had 2 interviews with Recruiter before actually talking to NG. All seemed very promising. Then had a full-day interview session with multiple interviewers at NG itself. These also went well. However, then "silence fell" as we say. Weeks and weeks later I got the dreaded "we'll keep you on file" letter.