Summary: On the cover of this book is a small quote 'Programmer to Programmer'. This is a very accurate statement. This book is not for the novice, it will cover most part of RHEL3, but it will immediatly jump to a advanced level on a wide variety of topics.
For example, How to configure XFree86 is only two paragraph's long, with reference to the 4 commands that work. No frills, just the facts to get you started.
Another example, where I learned a lot of facts, is the software RAID under Linux. I had not seen it described like here, with commands, explenations, troubleshooting tips, how to recover from emergencies, how to use RAID partition to backup databases. Great stuff.
This book can also be used as a cookbook, how to configure Postfix, SpamAssassin, VirtualDomains, SquirrelMail. Sure you can
find most of these informations on the internet, but here they are all pulled together tightly, and show how to work.
The Cluster section has a good description, hardware configurations tips, service configurations. etc... Other topics like security, CPAM, DNS with Transaction Signatures (TSIG), Monitoring network activities of your network with Nagios.
All in all, this is a great book for those administrative tasks on RHEL3 that you don't do every day, and are only hint to in all other books.