Cisco Human Resources interview questions

Submitted application in late September with just a resume. Heard back around late October to set up a video/phone interview with a recruiter who I had spoken to previously in an informational interview. Had to wait about two weeks to hear back about next steps even though the recruiter said it would only take a few days. Didn't get an offer and when I emailed the recruiter to ask what I was lacking, she vaguely said it came down to how prepared applicants were. Thought I did enough research and preparation but I guess not.

They were fast and efficient in arranging the interviews, went through a few rounds of positive interviews but the last round interviewer was rude. I got rejected with no reason given , it was rather odd to me.