Red Hat Enterprise Linux 5 supports LUKS encryption. True or False?
False. Red Hat Enterprise Linux 6 is the only version that officially supports LUKS encryption.
In Red Hat Enterprise Linux 6, SELinux is set to Enforcing by default during the installation. True or False?
True. In Red Hat Enterprise Linux 6, the default for SELinux is Enforcing during installation (which can be changed after the installation completes). For Red Hat Enterprise Linux 5, you were able to choose what mode you wanted SELinux to start in.
Which remote management service is installed by default? Can you name the port that it uses?
The SSH service is almost always installed by default in Red Hat. It uses TCP port 22, and this port is open on the default firewall rules.
You can install software packages only after Red Hat Enterprise Linux is installed. True or False?
False. The package selection screen allows you to install any software you want during the installation process as long as you have access to the correct packages or repositories.
The default partition layout includes only basic partitions. True or False?
False. The default partition layout for Red Hat Enterprise Linux 5 or 6 includes the use of LVM.
Which file contains all messages generated during installation that can be used for troubleshooting if the need arises?
The install.log.syslog file contains messages that are generated during the installation. If you run into trouble during the installation, this is a good place to start.
GRUB has three stages. Can you name them?
Stage 1: During this stage, the primary bootloader is read into memory by the BIOS from the MBR. Stage 1.5: During this stage, the bootloader is read into memory by the stage 1 bootloader (only if necessary). Stage 2: During this stage, the bootloader reads the operating system or kernel.
What option at the GRUB boot menu can you use to append something to a kernel?
By entering the GRUB boot menu, you can choose the a option to append something to the kernel command-line options.
The old SysInit scripts have been replaced in Red Hat Enterprise Linux 6 for what new boot utility?
Upstart. The Upstart utility is now used in the boot process for Red Hat Enterprise Linux 6.
Runlevel 0 reboots the system. True or False?
False. Runlevel 0 halts the system. Runlevel 6 reboots the system.
If your system crashes and becomes unbootable, you have to reinstall the whole operating system. True or False?
False. Most boot issues can be resolved by entering rescue mode and repairing the problem.
What command can you use to manage system services?
The service command is used to start, stop, and manage system services.
What command disables the SSH service from running when the system boots?
chkconfig sshd off
How can you list all services on the system to tell whether they will boot during startup?
What does S12rsyslog in the /etc/rc.d/rc2.d directory mean?
When the system enters into runlevel 2, the rsyslog service has a priority of 12 when starting. Anything with a lower number (or the same number and lower first letter) starts before the rsyslog service.
How can you verify the status of the SSH service after the system has booted?
service sshd statuts
What command and option can you use to enable a service to start on boot?
Use the chkconfig command to enable or disable services during the boot process. The on option enables the service and off disables it.
What option is used with both the fdisk and parted commands to display the current partition tables?
The print option is used with both the fdisk and parted commands to display the current partition tables.
What does the partprobe command do?
The partprobe command forces the kernel to reread the partition table. You should always call it after making any changes to your system partitions.
Do you need to write changes to the disk when using the parted command? What about fdisk?
When you exit the parted utility, all your changes are automatically written to disk. With the fdisk command, you need to manually write your changes to disk for them to take effect.
What are the three different types of RAID described in this chapter?
RAID 0 (Striping), RAID 1 (Mirror), and RAID 5 (Striping with parity).
What command can you use to query information from the kernel about RAID arrays?
Can you put your /boot partition on a RAID 5 array?
This is actually a trick question because the answer could go either way. In this chapter, we discussed only software RAID setups, in which case the answer is no. If, however, you were using a hardware RAID 5, the answer would be yes.
What are the three items that make up LVM?
Physical volumes, volume groups, and logical volumes.
What are the side effects of shrinking a volume group or logical volume?
If you shrink a volume group or logical volume, there is a chance you could lose data depending on how much you shrink the volume.
What is the biggest benefit to using LVM over basic partitions?
You have the flexibility to resize and add new volumes on the fly. With basic partitions, any time that you want to make a change, you need to destroy the partition and create it again.
What command can you use to get information about logical volumes?
What is the difference between an ext2 and ext3 file system?
An ext3 file system has journaling built in to it, whereas the ext2 file system doesn't.
What command can you use to create a file system?
Can you grow a file system?
Yes. Use the resize2fs command to grow a file system.
What is the superblock used for?
The superblock is a structure that contains metadata of the file system. If this becomes corrupt, you are in trouble.
What is a swap? Is it created as a partition or device file?
A swap is scratch space on your file system used as virtual memory. A swap can be created as a partition or a device file.
How can you check the currently mounted file systems?
The mount command lists all currently mounted file systems.
What file needs to be edited so that the system will mount a file system at boot time?
The /etc/fstab file.
Before you work with quotas, what do you need to do to the file system?
The file system where quotas will be implemented must be mounted with the usrquota and grpquota options before quotas will work properly.
What command do you use to change the permissions on a file or directory? To change ownership?
The chmod command is used to change the permissions of files and directories. The chown command is used to change the ownership of files and directories.
Explain the difference between soft and hard limits in quotas.
A soft limit acts like an alarm, signaling you when you are reaching your limit. If you don't specify a grace period, the soft limit is the max. A hard limit is required only when a grace period exists. It is the max limit you can hit before your grace period expires.
What command do you use to report information on quota usage?
Before you work with ACLs, what do you need to do to the file system?
The file system where ACLs will be implemented must be mounted with the acl option before ACLs will work properly.
What command can you use to view the current ACL on a file?
What command displays your current interfaces and IP address?
What does ifconfig 126.96.36.199 netmask 255.255.255.0 eth1 do?
This command sets the eth1 interface to have a static IP address of 188.8.131.52 with a netmask of 255.255.255.0.
What command can you use to test connectivity to another host?
The ping command can be used to verify connectivity to another host.
What does it mean if you ping a host and you receive the response Destination Unreachable?
The gateway is incorrectly set, and the subnet of the host you are trying to reach is inaccessible.
What is a gateway used for on a network?
A gateway is used as an entry and exit point for a subnet on a network. To contact hosts outside your subnet, you need to pass through a gateway.
How would you go about creating a static route?
Use the route command with the add option to create a static route.
What command can you use to monitor and troubleshoot network connections?
The tcpdump command is used to monitor network connections on different interfaces.
Can you name three utilities that can be used for network or DNS client troubleshooting?
The three utilities are: route, ping, and nslookup.
What is the /etc/hosts file used for?
The /etc/hosts file is a local lookup file used to map IP addresses to hostnames if a DNS server isn't available.
What two commands are used for package management?
The yum and rpm commands are used for package management.
What are the three modes in which the rpm command can operate?
The rpm command can operate in install, query, or verify modes.
What option would you use to query an installed package using the rpm command?
You can use the -q option to query an installed package. Combining grep and the -qa options, you can search among all installed packages on the system.
How would you install a group of packages all at a single time?
Use the yum groupinstall command to install multiple packages in a single group at once.
What options with the yum command would you use to remove a package?
You can use the remove or erase options with yum to remove a package.
Where are Yum repository config files located?
Yum repository config files (.repo files) are located in the /etc/yum.repos.d directory. You can also make direct entries into the main /etc/yum.conf file.
What command can you use to create your own repositories?
What command is used to create an RPM package?
What are the five required directories when building RPMS?
The five directories are BUILD, RPMS, SOURCES, SPECS, and SRPMS.
If a package is built on an RHEL6 system and deployed to a custom RHEL5 repository, are RHEL5 systems able to use it?
No. Red Hat Enterprise Linux 6 uses a different key to sign its packages.
What command (and options) can be used to create a user named JSmith with the description "Jr Admin"?
useradd -c "Jr Admin" JSmith
What is the format of the /etc/shadow file?
The format of the /etc/shadow file is <username>:<encrypted password>:<last passwd change>:<min>:<max>:<warn>:<inactive>:<expires>:<not used>.
What command would you use to create a group? How about to add the user JSmith to the group?
Use the groupadd command to create a group. You can then add user JSmith with the following: usermod -G <group name> JSmith
How do you run a command with elevated privileges?
You can use the sudo command to run a command with elevated privileges provided you have the rights in the /etc/sudoers file.
Is it possible to share files among groups? What permissions would you set on the directory to accomplish file sharing if possible?
Yes. You can use the setgid flag to create the appropriate permissions (chmod 2770).
If you want a specific action to take place when user01 logs in to the system, which file would you edit?
You add your action to the end of the /home/user01/.bashrc file.
You can add files to a user's home directory during creation. True or False?
True. Place all files you want added to a user's home directory in the /etc/skel directory.
By default, what is the path to a user's home directory?
A user's home directory is created under the /home directory.
What is the benefit to using centralized authentication?
By using centralized authentication, you don't need to re-create or maintain multiple accounts across every system in your organization.
What commands can you use to add a client machine to an LDAP server?
You can use the authconfig-tui command or the authconfig command.
Kickstart can be accomplished only by using a PXE server. True or False?
False. A PXE server eases the automation process but isn't required for kickstart installations to work.
What port on the firewall needs to be open for the TFTP server to work?
The TFTP server uses UDP port 69.
What three protocols can you use to perform network installations?
Network installations can be performed using the HTTP, FTP, and NFS protocols.
Can you create a RAID or LVM partition using kickstart?
Yes. Kickstart supports both basic and advanced partitioning (RAID/LVM).
It is possible to run scripts before a kickstart installation. True or False?
True. This is done by defining a %pre section although it is rarely used.
What is the name of the section used to run scripts after a kickstart installation?
By defining a %post section, you can run scripts after a kickstart installation is complete.
What three components are needed to fully automate a kickstart installation?
By combining a TFTP server, PXE boot, and DHCP server, you can fully automate the kickstart installation process.
What option can you change in the rsyslog config file to accept remote logs (acting as a centralized logging server)?
Uncomment the following line in the /etc/rsyslog.conf file:
What two commands are special for dealing with user login events?
The lastlog and faillog commands are used to view user login-related events?
Can you name the two commands that can be used to view the free space on the system?
The du and df commands are used to view available space on the system.
What command can you use to view system processes and their CPU usage?
Use the ps command to view processes and their CPU usage.
The at command is used to schedule reoccurring system jobs. True or False?
False. The at command is used to schedule one-time-only jobs. The cron service handles reoccurring system jobs.
What happens to jobs that are scheduled to run while the system is off?
When the system starts up again, the cron service will run any jobs that were missed while the system was off. On Red Hat Enterprise Linux 5, the anacron service handles this functionality.
What command can be used to view the queue for at service jobs?
What is the top command used for?
Use the top command to view CPU and memory usage.
What is the difference between the update (-U) and install (-i) options when using rpm to update the kernel?
You should never use the -U option because it erases the prior kernel when updating. This leaves you with no fallback kernel should your system not boot properly.
What directory is used to represent the virtual file system created by the kernel?
The /proc directory. The /proc/sys directory is the place where you actually tune kernel parameters.
What file is used to maintain custom parameters for the kernel during system boot?
The /etc/sysctl.conf file maintains a list of custom kernel parameters that should be applied during system boot.
What critical step must you take after updating the kernel to a newer version?
You must ensure that the /boot/grub/grub.conf file has the new entry for your newly updated kernel to be able to boot into it.