I got contacted by a recruiter on LinkedIn regarding a job opportunity at Gartner. I followed up immediately asking for the job description, but a reply never followed. After a week I got in touch again, as I was interested in Gartner. Again no reply. While I understand the position may have been filled in the meantime, it doesn't hurt to send a follow up and let a candidate know, especially if you'd been the one to get in touch. Radio silence looks both impolite and unprofessional - I imagine, not the way Gartner wants to present as a company.