OpenBSD is a project that develops and freely distributes multi-platform UNIX-like operating systems. The goal is to focus on security, correctness, standardization and also portability.
OpenBSD arranges FTP mirrors basing it on a master fanout site which is used to feed second level mirrors that other sites could retrieve and mirror from. The second level mirrors are sites that were chosen because they exhibit good network connectivity and are also known OpenBSD community of developers or those that support OpenBSD development and share those types of files. In maintaining a mirror site, find the nearest mirror site in your location. Mirroring from a master fanout site is highly recommended.