Ondřej Caletka is a network services operator and developer at CESNET, the Czech national research and educational network operator. He is responsible for the DNS and e-mail infrastructure, and IP resources management. He also encourages IPv6 deployment. Ondřej also writes technical articles for Root.cz and organises conferences and training courses like IPv6-day, Security Fest or LinuxDays in Prague. He is also a founding member of the CSNOG community.