Both files are mandatory. Part 1 contains the main installer and core binaries; Part 2 contains additional components (e.g., Java, examples, advanced queueing).

To verify file integrity after download, use sha256sum on Linux. Official checksums may be provided by Oracle in the README; here are typical published values (verify from Oracle documentation if possible):

Before you begin, ensure that your Linux system meets the minimum requirements for Oracle 11.2.0.4: