File pollution (i.e., sharing of corrupted files, or contaminating index information with bogus index records) is a de facto problem in many file sharing Peer-to-Peer (P2P) systems in use today. Since pollution squanders network resources and frustrates users with unprofitable downloads (due to corrupted files) and unproductive download trials (due to bogus index records), the viability of P2P systems (and similar distributed information-sharing applications) is questionable unless properly addressed. Thus, developing effective anti-pollution mechanisms is an immediate problem in this literature. This paper provides useful information and deep insight with future researchers who want to design an effective anti-pollution mechanism throughout an extensive measurement study of user behavior and file pollution in a representative DHT-based P2P system, the Kad network. ▸Keyword : Peer-to-Peer, File Sharing, Distributed System, File Pollution, Anti-pollution ∙제1저자, 교신저자 : 신규용 ∙투고일 : 2010. 10. 25, 심사일 : 2010. 12. 01, 게재확정일 : 2010. 12. 06. *육군사관학교 전자정보학과 (Dept. of Electrical Engineering and Information Science, Korea Military Academy) ※ 본 논문은 육군사관학교 화랑대연구소 2011년도 연구 활동비를 지원받아 연구되었음 132 韓國컴퓨터情報學會 論文誌(2011. 3.)