The Red Hat exams are based on your knowledge of Red Hat Enterprise Linux. When you take the RHCE exam, it'll be on a "standard" PC with Intel 32-bit (or compatible) personal computers. The CPU should have a speed of at least 700MHz, and the PC should have at least 256MB of RAM. As Red Hat Network updates are not explicitly listed as a requirement in the Red Hat Exam Prep guide, a "trial" subscription or a rebuild distribution is probably sufficient. If you want a full subscription, which can help you test features associated with the Red Hat Network, the price depends on your hardware and the amount of support you need. I've emphasized Red Hat solely to focus on distributions that use Red Hat source code, including the "rebuilds" described in this section (and more).
With Red Hat Enterprise Linux 5, Red Hat has modified its offerings into two categories:
RHEL Server includes varying levels of support for entry-level to high-end and mission-critical systems.
The RHEL Server Advanced Platform supports unlimited virtualized guests, virtualized storage, high-availability clustering and failover, with support for more than two CPUs.
RHEL Server subscriptions are available for IBM System Z mainframe systems on a per-processor basis.
RHEL Server subscriptions are also available for High Performance Computing clusters.
RHEL Desktop includes varying levels of support suitable for desktop computers and workstations. There are different options available for systems with one or more CPUs.
If you want to prepare for the RHCE exam with the official RHEL 5 server operating system, trial subscriptions are available (www.redhat.com/en_us/USA/home/developer/trial/). While they only support updates for 30 days, updates can also be tested using the mirror repositories associated with rebuild distributions. And you can download the same operating system (for the trial period) from the same sources as paying Red Hat users.
But you don't have to pay for the operating system or settle for a "trial subscription" to prepare for the RHCE exam. There are a wide variety of efforts to create "rebuilds" of Red Hat Enterprise Linux. The source code for almost all RHEL RPM packages is released under the Linux General Public License (GPL) or related licenses. This gives anyone the right to build Red Hat Enterprise Linux from the Red Hat released source code.
The source code is released in Source RPM package format, which means the RPM packages can be built using the rpm commands described in Chapter 5. The developers behind rebuild distributions have all revised the source code to remove Red Hat trademarks. Most, like CentOS-5, are freely available; others, like Oracle Linux, require a subscription.
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Oracle Linux has tried to undercut Red Hat by developing their own rebuild of Red Hat Enterprise Linux. Their subscriptions cost less at what I presume are similar support levels. As I have not tried Oracle Linux, I do not know if you get the same level of knowledge that you would get from Red Hat engineers.
You can select and download the rebuild that most closely meets your needs. I have tried several of the rebuilds, including those developed by Community Enterprise Linux (CentOS), Scientific Linux, and Lineox. All have proven reliable. In fact, they are so popular, some suggest that it has led to the demise of the Fedora Legacy project, which supported older versions of Fedora Core until December of 2006.
The rebuilds of RHEL are freely available; however, you should have a high-speed Internet connection. While these rebuilds do not use 100 percent RHEL software, I have not seen any difference that would impair your ability to study for the Red Hat exams.
Community Enterprise Linux The Community Enterprise Operating System (CentOS) rebuild developed by the group at www.centos.org appears solid to me. This group probably has the largest community (or at least gets the most publicity) among the rebuilds.
Scientific Linux Formerly known as Fermi Linux, it includes a lot of intellectual firepower associated with the Fermi National Accelerator Lab as well as CERN, the lab associated with Tim Berners-Lee, the person most commonly credited with the invention of the World Wide Web.
Lineox Lineox is based in Finland and offers priority updates for a fee. It may be especially interesting for people in the European Union, as their prices are in Euros. You can find out more about Lineox at www.lineox.net.
Alternatively, you can work from RHEL Desktop, if you're willing to install additional services from the source code. For more information on installing packages from source code, see Chapters 1, 5, and 8. Using the techniques described in Chapter 5, you can download the Red Hat Enterprise Linux Source RPMs at ftp.redhat.com, process them into binary RPMs, and then install them on your computer.
For the RHCE exams based on Red Hat Enterprise Linux 5, you can probably also work from Fedora Core 6, as RHEL 5 is based on this Red Hat community distribution.