One of the most valuable skills as a systems administrator is knowing how to troubleshoot a system. Understanding the scientific method is the first skill. Knowing how to boot into different runlevels and how to use the linux rescue mode from the first installation CD are other key skills.
The Troubleshooting and System Maintenance portion of the Red Hat exams includes RHCT and RHCE skills. If you're taking the RHCE exam, you'll need to pass both sections to qualify for the RHCE. The RHCT section requires that you know how to diagnose and correct misconfigured networking, diagnose and correct hostname resolution problems, configure the X Window System and a desktop environment, add new partitions and filesystems, and swap to existing systems. You also need to know how to use standard command line tools and configure your system. All of these skills were covered in this book and are summarized in this chapter.
RHCE candidates also have their own set of challenges during the Troubleshooting and System Maintenance portion of that exam. You'll need to know how to diagnose and correct boot failures arising from boot loader, module, and filesystem errors, as well as add, remove, and resize logical volumes. You'll also need to know how to diagnose and correct problems with any of the network services described throughout the book as well as related issues where SELinux is interfering with proper operation of these services.