By default, many Unix systems store the system logs in what format?

DB2 is a relational database management system from IBM, not a log storage format used by default on Unix systems.

ODBC (Open Database Connectivity) is an API standard for database access, not a file format for storing system logs.

XML is a structured markup format used in some application-level logging (e.g., log4j configurations), but it is not the default format for Unix system logs.

Unix-based operating systems, by default, write system logs (via syslog and similar daemons) as human-readable plain text using ASCII encoding. These files are stored in directories like /var/log/ and can be read with standard text utilities such as cat, grep, and tail without any special parsing software.