CompTIA Linux+ XK0-005 Cert Guide (Certification Guide)

Cover
Title Page
Copyright Page
Contents at a Glance
Table of Contents
Introduction
Part I: System Management (Obj. 1.1 - 1.7)
	Chapter 1: Understanding Linux Fundamentals
		“Do I Know This Already?” Quiz
		Foundation Topics
		Filesystem Hierarchy Standard
			What Goes Where in the FHS
			The Root of the Filesystem
			Where to Put Programs
		Basic Boot Process
			What Is the Boot Process?
			System Boot Options
			initrd and initramfs
			Booting with UEFI
			Booting via PXE
			Booting via NFS
			Booting via ISO
		Boot Loaders and Files
			GRUB Legacy
			GRUB2
			Changes Made for GRUB2
			GRUB2 Command Names
			Installing GRUB2
			Using the GRUB2 Command Line
			Demystifying Kernel Images
			Configuring GRUB2
			Common Commands at Boot Time
		When Kernels Panic
			Identifying a Kernel Panic
			Getting More Information
			Kernel Panic Causes
		Device Types in /dev
		Installing Software from Source
			Components of a Source Code Install
			The Makefile
			Example of a Compilation of Source Code
		Storage Concepts
			Partitions
			MBR
			GPT
			Data Storage Methods
			Block Storage
			File Storage
			Object Storage
			FUSE (Filesystem in Userspace)
			Why Use a FUSE?
			Handling FUSE User Requests
			Possible FUSE Applications/Uses
			RAID
			RAID Levels
			Mirroring
			Striping
			Parity
		Listing Your Hardware Info
			The Proc Filesystem
			Notable ls* Commands
			Friends of procfs
			The dmidecode Command
			Displaying DMI Table Information
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 2: Managing Files and Directories
		“Do I Know This Already?” Quiz
		Foundation Topics
		File and Directory Operations
			Tips for Working with Linux Files
			Basic Navigation
			Advanced Navigation
			Listing Files and Directories
			Touching Files
			Copying Files and Directories
			Moving Objects
			Creating and Removing Directories
			Removing Objects
		File Metadata and File Types
			Determining File Types
			The file Command
			Displaying File Metadata
			The stat Command
		Soft and Hard Links
			Linking Files
			Symbolic Links
			Hard Links
		File Compression, Archiving, and Backup
			Using tar
			Using Compression Utilities
			Using tar with Compression Utilities
			Taking Pity on the Unarchiver
			Useful Creation Options
			Listing Archive Files
			Using cpio
			Using the dd Command
			Compression Tools
			Backing Up Is Hard to Do
			Backup Types
			Other Backup Types
		Copying Objects Between Systems
			Using the scp Command
			Everything and the Kitchen rsync
			The nc Command
		File Editing
			The Message Line
			Editing in vim
			Opening a File for Editing
			Navigating Within a File
			Force Multipliers
			Undo Operations
			Saving Files
			Quitting vim
			Changing or Replacing Text
			Deleting Text and Lines
			Searching in vim
			Searching and Replacing
			nano, nano
			Why nano and Not Pico?
			nano’s Interface
			That’s a Wrap
		Feeling a Bit (awk)ward
		The printf Function
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 3: Configuring and Managing Storage
		“Do I Know This Already?” Quiz
		Foundation Topics
		Determining Storage Hardware
			Viewing SCSI Device Information
			Viewing Partition and Filesystem Device File Information
			The lsblk Command
			The blkid Command
			The (Non-Linux) fcstat Command
		Performing Disk Partitioning
			fdisk
			Partitioning with parted
			partprobe
		Inspecting and Managing Software RAID
			Creating and Inspecting a Software RAID
			Inspecting a Software RAID Device
		Using Logical Volume Manager (LVM)
			Overview of LVM
			Understanding Multipath
			Managing LVM
		Mounting Local and Remote Devices
			The Filesystem Table
			Manually Mounting Filesystems
			Unmounting Filesystems
			Using systemd to Mount
			Linux Unified Key Setup (LUKS)
		Monitoring Storage Space and Disk Usage
			Using iostat
			Using du
			Using df
		Filesystem Management
			Filesystem Checker
			EXT2/3/4 Tools Overview
			Tuning ext Filesystems
			Btrfs Tools
			XFS Commands
		Storage Area Networks/Network-Attached Storage
			SAN vs. NAS
			Multipathing with multipathd
			Typical Network Filesystems Used by SAN/NAS
			Samba vs. SMB and CIFS
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 4: Managing Processes and Services
		“Do I Know This Already?” Quiz
		Foundation Topics
		Managing Processes
			Viewing Processes
			What’s the Diff?
			The htop Command
			The free Command
			Blocks and Buffers
			Pages, Slabs, and Caches
			Interpreting Displayed Information from free
			Sending Signals to Processes
			Killing Processes by PID
			Using pgrep and pkill to Send Signals
			Killing Processes Using Other Criteria
			Finding What Is Using a Resource
			Introducing lsof
			Using lsof
			Job Control
			Managing Process Priorities
		systemd
			What’s Different About systemd?
			Units in systemd
			Unit File Directory Locations
			systemd Environment Variables
			systemd Targets and Runlevels
			Wants and Requires
			Booting with systemd
			Commands to Manage systemd
			The State of Services/Units
			Listing Services
			Enabling and Disabling Services
			Service Start, Stop, Restart, and Status
			Masking Services
		Scheduling Services
			Configuring crontabs
			Using the crontab Command
			Matching Times
			Spelling Out Month and Day Names
			Making Multiple Matches
			Step Values
			Putting Together the crontab
			Issues About PATH
			Dealing with Output
			Nicknames
			Other Files
			System crontabs
			Convenience crontabs
			Restricting Access
			Running ad hoc Jobs
			The at Command
			The batch Command
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 5: Using Network Tools and Configuration Files
		“Do I Know This Already?” Quiz
		Foundation Topics
		Interface Management
			iproute2
			Interface Management Commands
			The ip Command
			Examples of the ip Command
			The ss Command
			NetworkManager
			The nmtui Command
			The nmcli Command
			The net-tools Suite
			The ifconfig Command
			Configuring via ifcfg-* files and network-scripts
			On Debian-Based Systems
			The hostname Command
			The arp Command
			The route Command
		Name Resolution
			Configuring Name Resolution
			Controlling Resolution
			Setting Hostnames on systemd Systems
			The host, dig, and nslookup Commands
			The whois Command
		Network Monitoring
			Is the Remote Host Reachable?
			The ping Command
			The traceroute Command
			The mtr Command
			Is the Data Flowing Properly?
			Using netstat
			Swimming with Wireshark
			The tcpdump Command
		Remote Networking Tools
			SSH (Secure Shell)
			Using curl and wget
			The nc Command
			Using rsync
			Using scp
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 6: Building and Installing Software
		“Do I Know This Already?” Quiz
		Foundation Topics
		Package Management
			The Most Common Package Types
			Package Managers
			Debian Package Management
			Managing Local Debian Packages
			Installing Packages with dpkg
			Removing Packages
			Dependency Issues
			Querying Packages
			Reconfiguring Packages
			Using Repositories
			What Is a Repository?
			Viewing Configured Repositories
			Adding Repositories
			Installing Remote Packages
			Working with the Cache
			Upgrading the System
			Removing Packages
			Graphical Managers
			RPM and YUM Package Management
			The RPM Database
			RPM Package Files
			Package Name Conventions
			The rpm Command
			Validation of Packages
			Installation of Packages
			Additional Installation Options
			Verifying a Package’s Integrity
			Freshening vs. Upgrading
			Removing Packages
			Other Removal Options
			Querying Packages
			Package Management with YUM
			Installing Packages
			Fetching Updates
			Finding Packages to Install
			Configuring YUM
			Dandified YUM
			ZYpp
			Installing Software Packages with zypper
			Removing a Package with zypper
			Managing Repositories
		Sandboxed Applications
			What Is a Sandboxed App?
			App Sandbox Applications
			Flatpak
			AppImage
			Snapd
		System Updates
			Updating the Kernel
			Choosing an Update Method
			Reboot Methods
			Manual Update
			Update with Package Manager
			Linux Kernel Utilities
			No Reboot Method
			Live Kernel Patching Overview
			Issues with Live Patching
			The Live Patch Process
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 7: Managing Software Configurations
		“Do I Know This Already?” Quiz
		Foundation Topics
		Updating Configuration Files
			Restart or Reload?
			Restarting a Service
			Reloading a Service
			Grace Under Pressure
			Dealing with RPM Configurations
			Rage About Your Machine
			Two Methods to Retain the Original Configuration File
			Handling .rpmsave and .rpmnew Files
			Repository Configuration Files
			Repository Configuration File Overview
			The APT Configuration File
			The YUM Configuration File
			The DNF Configuration File
			Actual Repository Files
			The YUM Repo Files
			The APT Repo Files
		Configuring Kernel Options
			Viewing Kernel Parameters
			Doing It the Manual Way
			Getting Used to Using sysctl
			Ways to Set Kernel Parameters
			Using the sysctl.conf File
			Using the sysctl Command Directly
			Using /etc/sysctl.conf
			Using the sysctl Command to Load Parameters
			Understanding Kernel Modules
			Managing Kernel Modules
			Loading and Unloading Modules Manually
			The modprobe Command
		Configuring Common System Services
			Secure Shell (SSH)
			Network Time Protocol (NTP)
			NTP Expressed Through Chrony
			The timedatectl Command
			System Logging with Syslog
		Representing Locales
			Fallback Locales
			Contents of a Locale
			The localectl Command
			How Linux Uses the Locale
			systemd and syslog
			syslog
			The logger Command
			Configuring syslogd
			Key File Locations
			Other syslog Implementations
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
Part II: Security (Obj. 2.1 - 2.5)
	Chapter 8: Understanding Linux Security Best Practices
		“Do I Know This Already?” Quiz
		Foundation Topics
		Public Key Infrastructure
			Purpose of Certificates
			Certificate Authentication
			Self-Signed Certificates
			Certificate Authorities
			Private Keys
			Public Keys
			Encryption and Hashing
			Digital Signatures
		Certificate Use Cases
		Authentication
			Multifactor Authentication
			Tokens
			OTP
			Biometrics
			LDAP
			Pluggable Authentication Modules (PAMs)
			Password Policies
			Password Length
			LDAP Integration
			User Lockouts
			The /etc/pam.d Directory
			pam_tally2 and faillock
			System Security Services Daemon
			Single Sign-On (SSO)
		Linux Hardening
			The nmap Command
			The nc Command
			Secure Boot and UEFI
			System Logging Configurations
			Using umask
			Disabling/Removing Insecure Services
			Enforcing Password Strength
			Setting Password Parameters
			Aging Your Passwords
			No Wire Hangers (Group Passwords)
			Removing Unused Packages
			Tuning Kernel Parameters
			Securing Service Accounts
			Configuring the Host Firewall
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 9: Implementing Identity Management
		“Do I Know This Already?” Quiz
		Foundation Topics
		Account Creation and Deletion
			User Account Fundamentals
			What Accounts Are What?
			Regular User Accounts
			User Entries in /etc/passwd
			Special Login Files
			pam_tally2 and faillock
			Group Accounts
			Group Entries in /etc/group
			Group Passwords
			Adding Users and Groups
			Adding Users with useradd
			useradd Defaults
			skel Templates
			Adding Groups with groupadd
			Modifying Users and Groups
			Modifying User Accounts with usermod
			Modifying Groups with groupmod
			Removing Users and Groups
			Removing Users
			Removing Groups
			The Shadow Suite
			Encrypted Passwords and Shadow Fields
			/etc/shadow File Permissions
			Changing Passwords
			Aging Passwords
			A Login Shell Session
			A Non-Login Shell Session
			User Identity Query Options
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 10: Implementing and Configuring Firewalls
		“Do I Know This Already?” Quiz
		Foundation Topics
		Common Firewall Technologies
			iptables: Old and Reliable, but Complicated
			nftables: Newer, Tighter, More Dynamic
			firewalld: Newer, Flexible, Easier to Use
			UFW: Uncomplicated Indeed
		Understanding iptables
			Overview of Filtering Packets
			Important Terms
			Using iptables to Filter Incoming Packets
			Filtering by Protocol
			Multiple Criteria
			Filtering Based on Destination
			Changing the Default Policy
			Revisiting the Original Rules
			Saving the Rules
			Using iptables to Filter Outgoing Packets
			Stateful Rules
			Logging Rules
			Implementing NAT
		Additional Firewall Technologies
			The fail2ban Service
			DenyHosts
			IPset
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 11: Using Remote Connectivity for System Management
		“Do I Know This Already?” Quiz
		Foundation Topics
		SSH (Secure Shell)
			SSH Components
			Tunneling
			X11 Forwarding
			Port Forwarding
		Executing Commands as Another User
			The sudo Command
			The sudoedit Command
			User Privilege Escalation
			The su Command
			PolicyKit
			The pkexec Command
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 12: Understanding and Applying Access Controls
		“Do I Know This Already?” Quiz
		Foundation Topics
		File Permissions
			Permission Trio Bits
			Manipulating Permissions
			Octal Mode
			Symbolic Mode
		File and Directory Ownership
			Changing File Ownership
			Changing Group Ownership
		Understanding and Using umask
		Permission Granularity Issues
			Special Bit Permissions
			Setting the SUID Bit on Files
			Setting the SGID Bit on Files
			Setting the SGID Bit on Directories
			Setting the Sticky Bit
			Viewing and Changing File Attributes
			Displaying File Attributes
			Key File Attributes
			Setting File Attributes
			Removing File Attributes
		Finding Files by Permission
		Access Control Lists
			Not Enough Granularity
			ACLs to the Rescue
			Viewing ACLs
			Setting an ACL
			We All Wear Masks
		Context-Based Access
			Security-Enhanced Linux (SELinux)
			SELinux Mode
			SELinux Policy
			SELinux Booleans
			SELinux Contexts
			The audit2allow Command
			AppArmor
			aa-disable Command
			aa-complain Command
			aa-unconfined Command
			/etc/apparmor.d/ Directory
			/etc/apparmor.d/tunables Directory
		Command-Line Utilities
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
Part III: Scripting, Containers and Automation (Obj. 3.1 - 3.5)
	Chapter 13: Automating Tasks via Shell Scripting
		“Do I Know This Already?” Quiz
		Foundation Topics
		Shell Script Elements
			Globbing
		Environment Variables and Settings
			The PATH Variable
			The SHELL Variable
			Variable Expansion
			Running a Script
			Good Script Design
		Working with Input/Output Streams
			Standard In
			Standard Out
			Standard Error
			Find Errors on Demand
			Here Documents
			Redirection of Streams
			Redirecting Standard Input
			Redirecting Standard Output
			Redirecting Standard Error
			Redirection Redux
			Understanding /dev/tty
			Pipes
			Executing Multiple Commands
			Multiple Command Operators
			Command Substitution
			Splitting Streams with the tee Command
			Processing Output with the xargs Command
		Shell Script Elements
			Using the Output of Another Command
			Conditionals
			Testing Files
			An Easier Test Syntax
			Testing Strings
			Testing Integers
			Combining Multiple Tests
			case Statements
			switch Statements
			Loops
			For Loops
			Sequences
			while and until Loops
			Interacting with Other Programs
			Returning an Error Code
			Accepting Arguments
			Feeling a Bit (awk)ward
			Translating Files
			Cutting Columns
			He sed, She sed
			Using grep and Friends
			Getting a grep
			Examples of Using grep
			Review Questions
			Expanding grep with egrep and fgrep
			Using Regular Expressions and grep
			Pasting and Joining
			Finding Files
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
	Chapter 14: Performing Basic Container Operations
		“Do I Know This Already?” Quiz
		Foundation Topics
		Container Management
			Installing and Verifying the Container Tools
			Installing the Container-Tools Package and Dependencies
			Verifying the Podman and Skopeo Tool Installation
			Finding and Pulling a Container Image
			Finding a Suitable Image
			Pulling an Image
			Viewing and Inspecting Images
			Viewing Local Images
			Inspecting a Local Image
			Running an Image as a Container
			Assigning a Container-Friendly Name
			Detaching from and Attaching to Containers
			Exiting and Ending Execution of a Container
			Removing a Container
			Viewing Container Logs
			Exposing and Mapping Ports
		Container Image Operations
			build Command
			push Command
			pull Command
			list Command
			rmi Command
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 15: Performing Basic Version Control Using Git
		“Do I Know This Already?” Quiz
		Foundation Topics
		Version Control Concepts
			The First Generation
			The Second Generation
			What Is a Merge?
			The Third Generation
		Using Git for Version Control
			Installing Git
			Git Concepts and Features
			Git Stages
			Choosing Your Git Repository Host
			Configuring Git
			Using git tag
			Getting the Status of Files
			The .git Directory
			Telling Git to Ignore a File
			Handling Branches
			Executing Diffs
			Comparing Versions
			Dealing with Whitespace
			Comparing Branches
			Merging Files
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 16: Understanding Infrastructure as Code
		“Do I Know This Already?” Quiz
		Foundation Topics
		File Formats
			YAML
			Key Characteristics of YAML
			YAML Stream Examples
			JSON
			Key Characteristics of JSON
			JSON Examples
		Infrastructure as Code Concepts
			Just Making a Config Change
			Using Source Control
			Getting Started with IaC
			Utilities: Infrastructure as Code
			IaC Utility Choices
			Ansible
			Puppet and Chef
			Puppet
			Chef
			SaltStack
			Salt Architecture
			Salt Master Options
			Salt Configuration Locations
			Salt State Files
			Terraform
			Coding
			Planning
			Applying
		Continuous Integration/Continuous Deployment
			How Can It Be Solved?
			Continuous Integration
			Continuous Delivery
			CI/CD Use Cases
		Advanced Git Topics
			merge
			rebase
			Pull Requests
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 17: Understanding Containers, Cloud, and Orchestration
		“Do I Know This Already?” Quiz
		Foundation Topics
		Kubernetes Benefits and Application Use Cases
			What Is Kubernetes, Really?
			The High-Level Structure of Kubernetes
			Kubernetes Control Plane Structure
			Kubernetes Node Structure
			Container Runtime Interface
			Specialized Container Types
			Benefits of Using Kubernetes
		Single-Node Multicontainer Use Cases
			Two-Container Node Example A
			Two-Container Node Example B
			Three-Container Node Example
		Container Persistent Storage
			Docker Volumes
			Advantages of Using Docker Volumes
			Disadvantages of Using Docker Volumes
			Bind Mounts
			Advantages of Using Bind Mounts
			Disadvantages of Using Bind Mounts
			Kubernetes Persistent Volumes
			The Kubernetes PersistentVolume Subsystem
			The PV and PVC Lifecycles
		Container Networks
			What’s an Overlay Network?
			Docker Swarm
			Kubernetes Overlay Networks
			Bridging Networks
			Swotting a NAT
			Host Networking
		Service Mesh
			What Is a Service Mesh?
			Example Service Mesh
			Istio Components
			Commercial Istio Distributions
			Non-Istio Service Meshes
		Bootstrapping
		Container Registries
			What Is a Container Registry?
			What About Bigger Teams?
			What Are My Container Registry Options?
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
Part IV: Troubleshooting (Obj. 4.1 - 4.5)
	Chapter 18: Analyzing and Troubleshooting Storage Issues
		“Do I Know This Already?” Quiz
		Foundation Topics
		High Latency Issues
			High Latency Overview
			Causes and Symptoms of High Latency
			Diagnosing and Fixing High Latency
			Diagnosing with the top Command
			Diagnosing with the vmstat Command
			Fixing the Problem
		Low Throughput Issues
			Low Throughput Overview
			Causes and Symptoms of Low Throughput
			Diagnosing and Fixing Low Throughput
			Diagnosing with the df Command
			Diagnosing with the iostat Command
		Input/Output Operations per Second Scenarios
			IOPS Overview
			Scenario 1: Transferring Ten 500MB Files
			Scenario 2: Transferring 5,000 1MB Files
			Why IOPS Are Effectively Irrelevant
		Capacity Issues
			Causes and Symptoms of Capacity Issues
			Diagnosing and Fixing Capacity Issues
			Diagnosing with the df Command
			Diagnosing with the du Command
			Diagnosing with the find Command
		Filesystem Issues
			Filesystem Corruption Overview
			Causes and Symptoms of Filesystem Corruption
			Diagnosing and Fixing Filesystem Corruption
			Diagnosing and Fixing Filesystem Corruption with the fsck Command
			Summary
			Filesystem Mismatch Overview
			Causes and Symptoms of File Mismatch
			Diagnosing and Fixing File Mismatch
			Diagnosing a Mismatch Issue
			Fixing a Mismatch Issue
		I/O Scheduler Issues
			I/O Scheduler Overview
			Types of I/O Schedulers
			Viewing and Setting I/O Schedulers
			Viewing the Current I/O Scheduler
			Setting the Current I/O Scheduler
			Making the I/O Scheduler Change Persistent
		Device Issues
			NVMe Issues Overview
			Causes and Symptoms of NVMe Issues
			Diagnosing and Fixing NVMe Issues
			Using the nvme Command-Line Tool
			Solid-State Drive Issues Overview
			Causes and Symptoms of SSD Issues
			Diagnosing and Fixing SSD Issues
			SSD Trim
			Garbage Collection
			The TRIM Helper
			RAID Issues
			Causes and Symptoms of RAID Failures
			Diagnosing and Fixing RAID Failures
			Overview of Tools
			Monitoring and Alerting with smartd
			Checking Device Health with smartctl
			Monitoring RAID Array Health
			Monitoring RAID Array Health with mdadm
		LVM Issues
			LVM Troubleshooting Overview
			Causes and Symptoms of LVM Issues
			Diagnosing and Fixing LVM Issues
		Mount Option Issues
			Mounting Options Overview
			Causes and Symptoms of Mount Options Issues
			Diagnosing and Fixing Mount Option Issues
			Understanding Mount Option Gotchas
			What Are All These UUIDs in My fstab?
			What Is This errors= Option?
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 19: Analyzing and Troubleshooting Network Resource Issues
		“Do I Know This Already?” Quiz
		Foundation Topics
		Network Configuration Issues
			Causes and Symptoms of Network Configuration Issues
			Diagnosing and Fixing Network Configuration Issues
			Diagnosing Subnets with the ip Command
			Diagnosing Routes Using the ping Command
			Diagnosing Routes Using the ip route Command
			Diagnosing Routes Using the traceroute Command
		Firewall Issues
			Firewall Refresher
			What Could Possibly Go Wrong?
			Causes and Symptoms of Firewall Issues
			Diagnosing and Fixing Firewall Issues
			Diagnosing with the ping Command
			Diagnosing with the telnet Command
			Making Sure Services Are Running
		Interface Errors
			Dropped Packets and Collisions
			Diagnosing and Fixing Issues Related to Dropped Packets and Collisions
			Diagnosing with the ethtool Command
			Diagnosing with the netstat Command
			Diagnosing with the /sys/class/net//statistics Information
			Wrapping Up Dropping Packets
			Link Status
			Diagnosing and Fixing Link Status Issues
			Layer 1: Physical
			Layer 2: Data Link
		Bandwidth Limitations
			Bandwidth and Latency
			Diagnosing and Fixing Bandwidth Limitations
		Name Resolution Issues
			The Trifecta of DNS
			Diagnosing and Fixing Name Resolution Issues
		Testing Remote Systems
			How (Not) to Break the Law
			Purposes of Testing a Remote System
			Testing Remote Systems with NMAP
			Running a Simple System Scan
			Running a Service Discovery Scan
			Running a Vulnerability Scan
			Testing Remote Systems with s_client
			Verifying SSL Connection to a Remote System
			Other Useful s_client Commands
			Commands to Use when Connected to a Host
			Opening an SSL Connection to a Host
			Showing SSL Certificates on a Host
			Testing a Particular TLS Version on a Host
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 20: Analyzing and Troubleshooting CPU and Memory Issues
		“Do I Know This Already?” Quiz
		Foundation Topics
		Runaway and Zombie Processes
			Runaway Processes
			What Causes Runaway Processes?
			Reserving Some CPU for Non-Realtime Processes
			Identifying a Runaway Process
			Ending a Runaway Process
			Zombie Processes
			What Causes Zombie Processes?
			Are Zombie Processes Bad?
			Removing Zombie Processes
		High CPU Utilization/Load Average/Run Queues
			High CPU Utilization
			High Load Average
			Viewing System Load Details with the uptime Command
			High Run Queues
			Viewing System Load Details with the tload Command
		CPU Times and CPU Process Priorities
			Measuring CPU Time
			Important CPU Time Terms
			CPU Process Priorities
		Memory Exhaustion and Out of Memory
			What Is Out of Memory (OOM)?
			Memory Leaks
			The Process Killer
		Swapping
			Swap, Caching, and Buffers
			Blocks and Buffers
			Pages, Slabs, and Caches
			How Much Swap Is Enough?
		Hardware
			Viewing CPU Info
			Viewing Memory Info
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 21: Analyzing and Troubleshooting User and File Permissions
		“Do I Know This Already?” Quiz
		Foundation Topics
		User Login Issues
			Inspecting Account Details
			ID Please
			Get Entity
			Case-Sensitivity
			Has the User Ever Logged In?
			The last Command
			The lastlog Command
		User File Access Issues
			Group Issues
			Context Issues
			Permission Issues
			ACL Issues
			Attribute Issues
			Policy/Non-Policy Issues
		Password Issues
			The faillog Command
			/etc/security.access.conf
		Privilege Elevation Issues
		Quota Issues
			Possible Files or Entirety of Blocks?
			Converting to Usable Numbers
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 22: Analyzing and Troubleshooting Common Problems Using Systemd
		“Do I Know This Already?” Quiz
		Foundation Topics
		Unit Files
			Service Unit File Issues
			Networking Services
			ExecStart and ExecStop
			Before and After
			Type
			User
			Requires and Wants
			Timer Unit File Issues
			OnCalendar
			OnBootSec
			Unit
			Time Expressions
			Mount Unit File Issues
			Naming Conventions
			What
			Where
			Type
			Options
			Target Unit File Issues
			Default
			Multiuser
			Network-online
			Graphical
		Common Problems
			Name Resolution Failure
			Application Crash
			Time-Zone Configuration
			Boot Issues
			Journal Issues
			Services Not Starting on Time
		Summary
		Exam Preparation Tasks
		Review All Key Topics
		Define Key Terms
		Review Questions
	Chapter 23: Final Preparation
		Exam Information
		Getting Ready
		Tools for Final Preparation
			Pearson Test Prep Practice Test Software and Questions on the Website
			Accessing the Pearson Test Prep Practice Test Software Online
			Accessing the Pearson Test Prep Practice Test Software Offline
			Customizing Your Exams
			Updating Your Exams
			Premium Edition
			Chapter-Ending Review Tools
		Suggested Plan for Final Review/Study
		Summary
Appendix A: Answers to the “Do I Know This Already?” Quizzes and Review Questions
Glossary
	A
	B
	C
	D
	E
	F
	G
	H
	I
	J
	K
	L
	M
	N
	O
	P
	Q
	R
	S
	T
	U
	V
	Z
Index
	A
	B
	C
	D
	E
	F
	G
	H
	I
	J
	K
	L
	M
	N
	O
	P
	Q
	R
	S
	T
	U
	V
	W
	X
	Y
	Z
Online Elements
	Appendix B: Study Planner