RHCE Red Hat Certified Engineer Linux Study Guide (Exam RH302),

732 Pages·2009·5.13 MB·English

RHCE Red Hat Certified Engineer Linux Study Guide (Exam
RH302), Fifth Edition
by Michael Jang
McGraw-Hill/Osborne © 2007 (896 pages)
ISBN:9780072264548
With hundreds of practice questions and hands-on exercises, this
authoritative guide covers what you need to know--and shows you
how to prepare--for the challenging RHCE exam (RH302).
Table of Contents
RHCE Red Hat Certified Engineer Linux Study Guide (Exam
RH302), Fifth Edition
Preface
Introduction
Chapter 1 - RHCE Prerequisites
Chapter 2 - Hardware and Installation
Chapter 3 - The Boot Process
Chapter 4 - Linux Filesystem Administration
Chapter 5 - Package Management
Chapter 6 - User Administration
Chapter 7 - System Administration Tools
Chapter 8 - Kernel Services and Configuration
Chapter 9 - Apache and Squid
Chapter 10 - Network File-Sharing Services
Chapter 11 - Domain Name Service
Chapter 12 - Electronic Mail
Chapter 13 - Other Networking Services
Chapter 14 - The X Window System
Chapter 15 - Securing Services
Chapter 16 - Troubleshooting
Appendix A - Sample Exam 1
Appendix B - Sample Exam 2
Glossary
Index
List of Figures
List of Tables
List of Exercises
List of Exam Details
1
Getting Red Hat Enterprise Linux
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.
o The RHEL Server Advanced Platform supports unlimited virtualized
guests, virtualized storage, high-availability clustering and failover, with
support for more than two CPUs.
o RHEL Server subscriptions are available for IBM System Z mainframe
systems on a per-processor basis.
o 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
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remove Red Hat trademarks. Most, like CentOS-5, are freely available; others,
like Oracle Linux, require a subscription.
On the Oracle Linux has tried to undercut Red Hat by developing
Job 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.
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In This Book
The Red Hat RHCT and RHCE exams are designed to test candidate
qualifications as Linux systems technicians and engineers. If you pass either of
these exams, it's not because you've memorized a canned set of answers—it's
because you have a set of Linux administrative skills and know how to use them
under pressure, whether it be during an exam or in a real-world situation.
While this book is organized to serve as an in-depth review for the RHCT and
RHCE exams for both experienced Linux and Unix professionals, it is not
intended as a substitute for Red Hat courses, or more importantly, real-world
experience. Nevertheless, each chapter covers a major aspect of the exam, with
an emphasis on the "why" as well as the "how to" of working with and supporting
RHEL as a systems administrator or engineer. As the actual RHCT and RHCE
Exam Prep guide (www.redhat.com/rhce/examprep.html) changes with every
release of RHEL (and even sometimes between releases), refer to the noted
URL for the latest information. (Throughout the book, I often refer to the RHCT
and RHCE Exam Prep guide as the Red Hat Exam Prep guide, even though
there are Red Hat exams for certifications other than the RHCT and RHCE.)
Red Hat says it's important to have real-world experience to pass their exams,
and they're right! However, for the RHCT and RHCE exams, they do focus on a
specific set of Linux administrative skills, as depicted in the Red Hat Exam Prep
guide. This book is intended to help you take advantage of the skills you already
have—and more importantly, brush up in those areas where you may have a bit
less experience.
This book includes relevant information from Red Hat Enterprise Linux 5 (RHEL
5). There are significant changes from Red Hat Enterprise Linux 4; As of this
writing, Red Hat even offers a course detailing the differences (RHUP 304 and
RHUP 305). Several key differences between RHEL 4 and RHEL 5 include:
 A new hardware detection model. The udev system readily supports
automatic mounting and configuration of a wide variety of devices.
 Multicore support. Fundamental to effective virtualization, multicore CPUs
can help multiple operating systems run simultaneously on the same physical
system. Red Hat includes Xen in RHEL 5 to take advantage of the latest
multicore CPUs.
 Logical Volume Management (LVM), version 2, which supports smoother
resizing of filesystems.
 Software RAID now supports more modes, including RAID 6. The associated
tool is more flexible.
 NFS supports "stateless" network and loopback images.
 yum replaces Up2Date for repository and package management as well as
updates.
 The Network Manager incorporates improvements in wireless networking and
more, which eases administration on the desktop.
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 SELinux is now easier to use and administer. The descriptions in the Security
Level Configuration tool are improved, and sealert -b browser can help you
diagnose many SELinux-related issues.
There are many more key features; those that I believe are relevant to the RHCT
and RHCE exams, as defined by the publicly available course outlines and the
Exam Prep guide, are also included in this book.
While it's a risky practice in service, it is fastest to administer RHEL during the
exam by logging into the root user account. The command prompt and PATH
assume use of that account. When you're logged into the root account, you'll see
a command line prompt similar to:
[
In Every Chapter
For this series, we've created a set of chapter components that call your attention
to important items, reinforce important points, and provide helpful exam-taking
hints. Take a look at what you'll find in every chapter:
 Every chapter begins with the Certification Objectives—the skills you need
to master in order to pass the section on the exam associated with the
chapter topic. The Objective headings identify the objectives within the
chapter, so you'll always know an objective when you see it.
 Exam Watch notes call attention to information about, and potential pitfalls
in, the exam. These helpful hints are written by authors who have taken the
exams and received their certification—who better to tell you what to worry
about? They know what you're about to go through!
 Practice Exercises are interspersed throughout the chapters. These are
step-by-step exercises that allow you to get the hands-on experience you
need in order to pass the exams. They help you master skills that are likely to
be an area of focus on the exam. Don't just read through the exercises; they
are hands-on practice that you should be comfortable completing. Learning
by doing is an effective way to increase your competency with a product.
Remember, the Red Hat exams are entirely "hands-on;" there are no multiple
choice questions on these exams.
On the notes describe the issues that come up most often in real-
Job world settings. They provide a valuable perspective on
certification- and product-related topics. They point out
common mistakes and address questions that have arisen
from on-the-job discussions and experience.
Inside the Exam sidebars highlight some of the most common and confusing
problems that students encounter when taking a live exam. Designed to
anticipate what the exam will emphasize, getting inside the exam will help ensure
you know what you need to know to pass the exam. You can get a leg up on how
to respond to those difficult-to-understand labs by focusing extra attention on
these sidebars.
 Scenario & Solution sections lay out potential problems and solutions in a
quick-to-read format.
 The Certification Summary is a succinct review of the chapter and a
restatement of salient skills regarding the exam.
 The Two-Minute Drill at the end of every chapter is a checklist of the main
points of the chapter. It can be used for last-minute review.
 The Self Test offers "fill in the blank" questions designed to help test the
practical knowledge associated with the certification exams. The answers to
these questions, as well as explanations of the answers, can be found at the
end of each chapter. By taking the Self Test after completing each chapter,
you'll reinforce what you've learned from that chapter.
 The Lab Questions at the end of the Self Test section offer a unique and
challenging question format that requires the reader to understand multiple
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chapter concepts to answer correctly. These questions are more complex
and more comprehensive than the other questions, as they test your ability to
take all the knowledge you have gained from reading the chapter and apply it
to complicated, real-world situations. Most importantly, the Red Hat exams
contain only lab type questions. If you can answer these questions, you have
proven that you know the subject!
Online Learning Center
If you'd rather take an electronic version of the Self Test questions and answers,
these can also be accessed online through the book's Online Learning Center.
These online exams should not stand in for an actual practice test and are not
test simulations. You should complete the practice exams printed at the back of
the book for a more accurate simulation of the live exam and the exam
environment. The bonus content accompanying the book can also be located at
the Online Learning Center.
All you need to access the Online Learning Center is an Internet connection and
the following URL: http://highered.mhhe.com/sites/0072264543/.
The site also contains two Appendixes that accompany the book, available for
download:
 "Installing Red Hat Enterprise Linux 5"
 "Studying with a Virtual Machine"
To access the bonus content once you have located the site, select View Student
Content or click Returning Users and you should have access to all the available
material. Use the drop-down menu to navigate the site.
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Some Pointers
Once you've finished reading this book, set aside some time to do a thorough
review. You might want to return to the book several times and make use of all
the methods it offers for reviewing the material:
 Reread all the Exam Watch notes. Remember that these notes are written by
authors who have taken the exam and passed. They know what you should
expect—and what you should be on the lookout for.
 Review all the Scenario & Solution sections for quick problem solving.
 Retake the Self Tests. Focus on the labs, as there are no multiple choice (or
even "fill in the blank") questions on the Red Hat exams. I've included "fill in
the blank" questions just to test your mastery of the practical material in each
chapter.
 Complete the exercises. Did you do the exercises when you read through
each chapter? If not, do them! These exercises are designed to cover exam
topics, and there's no better way to get to know this material than by
practicing. Be sure you understand why you are performing each step in
each exercise. If there is something you are not clear on, reread that section
in the chapter.
Introduction
The Red Hat Exam Challenge
This section covers the reasons for pursuing industry-recognized certification,
explains the importance of your RHCE or RHCT certification, and prepares you
for taking the actual examination. It gives you a few pointers on how to prepare,
what to expect, and what to do on exam day.
Leaping Ahead of the Competition!
Red Hat's RHCT and RHCE certification exams are hands-on exams. As such,
they are respected throughout the industry as a sign of genuine practical
knowledge. If you pass, you will be head and shoulders above the candidate who
has passed only a "standard" multiple-choice certification exam.
There are two parts to both RHCT and RHCE exams, as follows. The
requirements are detailed in the Exam Readiness Checklist later in this
introduction.
 Section I Troubleshooting and System Maintenance: (RHCE) 2.5 hours
(RHCT) 1.0 hours. As described in the Red Hat Exam Prep guide, RHCE
candidates need to meet the requirements for both Red Hat certifications.
Both RHCT and RHCE candidates must complete all five RHCT
Troubleshooting and System Maintenance problems within the first hour. As
there are five "optional problems," RHCEs need to complete three of five of
these RHCE-level problems for an overall score of 80 on this section.
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 Section II Installation and Configuration: (RHCE) 3.0 hours (RHCT) 2.0
hours. As described in the Red Hat Exam Prep guide, RHCE candidates
need to meet the requirements for both the RHCT and RHCE. RHCT
candidates need a grade of 70 or higher on their section. RHCE candidates
must get a grade of 70 or higher on both the RHCT and RHCE components
of the Installation and Configuration section of your exam.
Why a Hands-On Exam?
Most certifications today are based on multiple-choice exams. These types of
exams are relatively inexpensive to set up and easy to proctor. Unfortunately,
many people without real-world skills are good at taking multiple-choice exams.
This results in problems on the job with "certified" engineers, who have an image
as "paper tigers" who do not have any real-world skills.
In response, Red Hat wanted to develop a certification program that matters. For
the most part, they have succeeded with the RHCT, RHCE, and their other
advanced certifications.
Linux administrators frequently debug computers with problems. The challenges
in the Troubleshooting and System Maintenance sections are based on real-
world problems. As the typical Linux administrator has to work through multiple
challenges on a daily basis, the RHCE Troubleshooting and System Maintenance
section provides a credible measure of real-world skills.
Linux administrators sometimes have to install Linux on a computer or virtual
machine. Depending on the configuration, they may need to install Linux from a
central source through a network. Installing Linux is not enough to make it useful.
Administrators need to know how to configure Linux: add users, install and
configure services, create firewalls, and more.
Exam Watch
The RHCT and RHCE exams are Red Hat exams. Knowledge of System V or
BSD-based Unix is certainly helpful, as well as experience with services like
Apache, SMB, NFS, DNS, iptables, and DHCP. But it is important to know how to
set up, configure, install, and debug these services under Red Hat Enterprise
Linux (or rebuild distributions that use the same source code, such as CentOS,
Scientific Linux, or Lineox).
Preparing for the RHCT and RHCE Exams
The RHCT is a complete subset of the RHCE. In other words, if you're studying
for the RHCT, use this book, based on the guidelines listed in Table 2, at the end
of this introduction. If you're studying for the RHCE, read the whole book. The
RHCE exam includes every aspect of the RHCT exam.
Work with Red Hat Enterprise Linux. Install it on a computer (or virtual machine)
that you don't need for any other purpose. Configure the services described in
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this book. Find ways to break network services and make Linux unbootable,
study the characteristics of the problem, and find different ways to fix the
problem.
As you go through this book, you'll have the opportunity to install RHEL several
times. If you have more than one computer, you'll be able to install RHEL over a
network. And you should, as network installations are explicitly listed in the Exam
Prep guide. Then you can work with the different network services. Test out each
service as you configure it, preferably from another computer on your network.
Testing your work becomes especially important when you start working with the
security features of Linux.
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