Open ca221.part1.rar using a tool like 7-Zip or WinRAR.
Files labeled "CA" often appear in city planning or technical manuals, such as those found in Petaluma's city records .
If you can tell me or what you expect to be inside (like a game, a book, or music), I can give you more specific instructions! 440 BLACK OAK DRIVE - IIS Windows Server - City of Petaluma
Often used on the Internet Archive for large collections of music, software, or scanned texts.