RHCSA

Instructions:

• Answer 50 questions in 15 minutes.
• If you are not ready to take this test, you can study here.
• Match each statement with the correct term.
• Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. What command can you use to query Boolean values?
A virtual host is a way of hosting multiple sites using a single IP address.
getsebool -a | grep http
SELinux provides enhanced granular security for the Linux operating system.
getsebool


2. What command disables the SSH service from running when the system boots?
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.
The anonymous_enable=YES option in the main config file allows anonymous uploads.
chkconfig sshd off
The user_list file can be used to limit which users have access to the FTP server.


3. What command-line program can you use to check your mail?
The tcpdump command is used to monitor network connections on different interfaces.
Typing the mail or mutt command allows you to read mail from the command line.
The du and df commands are used to view available space on the system.
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.


4. What command can you use to create a password-protected page?
The TFTP server uses UDP port 69.
The htpasswd command can be used to password-protect a web page.
Kickstart supports both basic and advanced partitioning (RAID/LVM).
export one or all resources


5. What two ports should be opened on the firewall for the FTP server to function properly?
halts the system
You must open TCP ports 20 and 21 for the FTP server to function properly.
If you are a hosting company or want to run multiple websites/applications from a single IP address - you can use virtual hosts to accomplish this.
The /etc/exports file needs to contain any directory that you want to export - including which options you'd like to use as well.


6. What is the benefit to using centralized authentication?

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7. FTP is one of three protocols ______________. The other two protocols are NFS and HTTP.
The du and df commands are used to view available space on the system.
Kickstart supports both basic and advanced partitioning (RAID/LVM).
used for kickstart and/or network installs
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.


8. A service needs to have _______________ to be able to use it.
support for TCP Wrappers
You should never allow remote root access. Should your root account become compromised and you use the same password - someone could gain access to all your systems. You also don't want the most powerful user of your system (with no accountability) l
SSH is used for secure remote management of Linux systems.
user's home directory in the /etc/skel directory


9. What command do you use to change the permissions on a file or directory - To change ownership?
support TCP Wrappers
The yum and rpm commands are used for package management.
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.
The /proc directory. The /proc/sys directory is the place where you actually tune kernel parameters.


10. What is the format of the /etc/shadow file?
By combining a TFTP server - PXE boot - and DHCP server - you can fully automate the kickstart installation process.
The format of the /etc/shadow file is <username>:<encrypted password>:<last passwd change>:<min>:<max>:<warn>:<inactive>:<expires>:<not used>.
Using the host option in the dhcpd.conf file allows you to reserve a client IP address based on its MAC address.
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.


11. What command can you use to validate the syntax of the Apache config file?
schedule one-time-only jobs
service httpd configtest
repquota
A large warning message appears indicating that the key doesn't match the host you are connecting to. You have to remove the key/host pair from the known_hosts file to proceed.


12. Which file contains all messages generated during installation that can be used for troubleshooting if the need arises?
After the ntpd service is stopped - you can use the ntpdate <server> command to update/sync the time.
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.
service named configtest
The TFTP server uses UDP port 69.


13. What is the /etc/hosts file used for?

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14. The ______________ for Red Hat Enterprise Linux 5 or 6 includes the use of LVM.
Use the top command to view CPU and memory usage.
generates errors under Red Hat Enterprise Linux 6
LUKS encryption
Enforcing during installation


15. What three protocols can you use to perform network installations?
The file system where quotas will be implemented must be mounted with the usrquota and grpquota options before quotas will work properly.
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.
Network installations can be performed using the HTTP - FTP - and NFS protocols.
For Apache to run a secure site - the mod_ssl package is required to be installed.


16. 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.
The two main config files are master.cf and main.cf.
The rndc utility provides a method for managing the DNS server remotely and securely.
semanage boolean -l


17. What does ifconfig 172.168.1.100 netmask 255.255.255.0 eth1 do?
This command sets the eth1 interface to have a static IP address of 172.168.1.100 with a netmask of 255.255.255.0.
After the ntpd service is stopped - you can use the ntpdate <server> command to update/sync the time.
The two main config files are master.cf and main.cf.
A virtual host is a way of hosting multiple sites using a single IP address.


18. Place all files you want added to a _______________ during creation.

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19. GRUB has three stages. Can you name them?
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.
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.
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 bootlo
Physical volumes - volume groups - and logical volumes.


20. Through its main config file - SSH can be configured to...

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21. What two commands are used for package management?
By defining a %post section - you can run scripts after a kickstart installation is complete.
The grep -v ^# /etc/vsftpd/vsftpd.conf command shows you all the options currently being used with the FTP server.
The yum and rpm commands are used for package management.
The file system where quotas will be implemented must be mounted with the usrquota and grpquota options before quotas will work properly.


22. The old SysInit scripts have been replaced in Red Hat Enterprise Linux 6 for what new boot utility?
chkconfig xinetd --list
The /etc/exports file needs to contain any directory that you want to export - including which options you'd like to use as well.
service dhcpd configtest
Upstart. The Upstart utility is now used in the boot process for Red Hat Enterprise Linux 6.


23. How can you verify the status of the SSH service after the system has booted?
getsebool -a | grep http
generates errors under Red Hat Enterprise Linux 6
Version 2 is the latest and most secure version of SSH.
service sshd statuts


24. What three commands can you use to help verify that the DNS server is functioning properly?
The anonymous_enable=YES option in the main config file allows anonymous uploads.
The dig - host - and ping commands can be used to test DNS server functionality.
The lastlog and faillog commands are used to view user login-related events?
Use the route command with the add option to create a static route.


25. The virt-install package allows you to manage virtual machines _____________. The virt-manager package allows you to manage virtual machines via a GUI interface.
The lftp command can be used on a client to test FTP server connections.
No. Red Hat Enterprise Linux 6 uses a different key to sign its packages.
via the command line
A web proxy can provide multiple benefits - including security - web page caching for faster load times - and load balancing.


26. 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.
VNC is used to control a remote desktop session.
The rpm command can operate in install - query - or verify modes.
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.


27. What are the three items that make up LVM?
have the same effect
A virtual host is a way of hosting multiple sites using a single IP address.
service dhcpd configtest
Physical volumes - volume groups - and logical volumes.


28. What command and options can you use to update the time?
After the ntpd service is stopped - you can use the ntpdate <server> command to update/sync the time.
SELinux Booleans provide restrictions to different aspects of a service.
LUKS encryption
service dhcpd configtest


29. The INPUT chain being used is the default under Red Hat Enterprise Linux 5. This rule...
An A record translates translated hostnames to IP addresses - and a PTR record works the other way around.
If you are a hosting company or want to run multiple websites/applications from a single IP address - you can use virtual hosts to accomplish this.
generates errors under Red Hat Enterprise Linux 6
RAID 0 (Striping) - RAID 1 (Mirror) - and RAID 5 (Striping with parity).


30. Most boot issues can be resolved by...
The lftp command can be used on a client to test FTP server connections.
choose which mode you'd like it to operate in
entering rescue mode and repairing the problem.
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.


31. The at command is used to ____________. The cron service handles reoccurring system jobs.
kickstart installations to work
Uncomment the following line in the /etc/rsyslog.conf file: #$ModLoad imudp.so #$UDPServerRun 514
schedule one-time-only jobs
The SMTP service runs on TCP port 110.


32. How can you check the currently mounted file systems?
After the ntpd service is stopped - you can use the ntpdate <server> command to update/sync the time.
via the command line
The /var/log/audit/audit.log file contains all policy violations.
The mount command lists all currently mounted file systems.


33. Which version of SSH should you use?
Version 2 is the latest and most secure version of SSH.
Upstart. The Upstart utility is now used in the boot process for Red Hat Enterprise Linux 6.
entering rescue mode and repairing the problem.
The five directories are BUILD - RPMS - SOURCES - SPECS - and SRPMS.


34. What command displays your current interfaces and IP address?
You can use the remove or erase options with yum to remove a package.
ifconfig
browseable option
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.


35. How would you install a group of packages all at a single time?
Network installations can be performed using the HTTP - FTP - and NFS protocols.
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.
A virtual host is a way of hosting multiple sites using a single IP address.
Use the yum groupinstall command to install multiple packages in a single group at once.


36. What happens if you call the command from question 3 with the -c option after it has already been run?
The file that stores usernames and their encrypted passwords is erased and replaced with a new file.
The rdnc-confgen command generates an rndc.conf file for the rndc utility.
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.
The firewall rule is inserted into the fifth line of the iptables rules and opens up TCP port 80 (for the HTTP service) on the firewall to allow incoming connections.


37. What option would you use to query an installed package using the rpm command?
A large warning message appears indicating that the key doesn't match the host you are connecting to. You have to remove the key/host pair from the known_hosts file to proceed.
getsebool -a | grep http
createrepo
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.


38. What command can you use to view NFS statistics?
The SMTP service runs on TCP port 110.
PAM is used as a modular way to leverage security. In this chapter - the main function we discussed was for managing password policies and complexity.
atq
The nfsstat command can be used to view NFS statistics.


39. What file needs to be edited so that the system will mount a file system at boot time?
The /etc/fstab file.
By combining a TFTP server - PXE boot - and DHCP server - you can fully automate the kickstart installation process.
The last rule is always an implicit deny statement rejecting anything that wasn't matched by previous rules.
If you are a hosting company or want to run multiple websites/applications from a single IP address - you can use virtual hosts to accomplish this.


40. What happens if a host changes its IP address and the keys don't match?

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41. What port does the Apache web server run on - What about HTTPS?
Apache uses port 80 for HTTP and port 443 for HTTPS.
alternatives --config mta
support for TCP Wrappers
The user_list file can be used to limit which users have access to the FTP server.


42. What option can you change in the rsyslog config file to accept remote logs (acting as a centralized logging server)?
The five directories are BUILD - RPMS - SOURCES - SPECS - and SRPMS.
Uncomment the following line in the /etc/rsyslog.conf file: #$ModLoad imudp.so #$UDPServerRun 514
Use the setgid flag to create the appropriate permissions (chmod 2770).
The smbstatus command shows you currently mounted Samba resources.


43. What does the partprobe command do?
You can use the sudo command to run a command with elevated privileges provided you have the rights in the /etc/sudoers file.
A large warning message appears indicating that the key doesn't match the host you are connecting to. You have to remove the key/host pair from the known_hosts file to proceed.
The partprobe command forces the kernel to reread the partition table. You should always call it after making any changes to your system partitions.
By default - Squid runs on port 3128.


44. What option at the GRUB boot menu can you use to append something to a kernel?
The superblock is a structure that contains metadata of the file system. If this becomes corrupt - you are in trouble.
Use the route command with the add option to create a static route.
By entering the GRUB boot menu - you can choose the a option to append something to the kernel command-line options.
This command sets the eth1 interface to have a static IP address of 172.168.1.100 with a netmask of 255.255.255.0.


45. How can you display all virtual guests after they're connected to a hypervisor?
The grep -v ^# /etc/vsftpd/vsftpd.conf command shows you all the options currently being used with the FTP server.
Use the setgid flag to create the appropriate permissions (chmod 2770).
rpmbuild
After you connect to a hypervisor - you can use virsh list —all to list all virtual guests.


46. What command can you use to test the config files before starting the DNS service?
Enforcing during installation
The rndc utility provides a method for managing the DNS server remotely and securely.
Public/private key authentication provides an additional layer of security because you need the correct key instead of just knowing someone's password. Passwords combined with public/private keys take the security one additional step.
service named configtest


47. What is the xinetd service used for?
Use the setgid flag to create the appropriate permissions (chmod 2770).
amount of RAM
The grep -v ^# /etc/vsftpd/vsftpd.conf command shows you all the options currently being used with the FTP server.
The xinetd daemon is used to control and/or run multiple system services. One example is a TFTP server.


48. What command can you use to get information about logical volumes?
The print option is used with both the fdisk and parted commands to display the current partition tables.
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.
lvdisplay
service named configtest


49. The firewall service is...
The superblock is a structure that contains metadata of the file system. If this becomes corrupt - you are in trouble.
enabled by default
By default - the rndc utility listens on port 953.
The TFTP server uses UDP port 69.


50. Where are Yum repository config files located?
The rdnc-confgen command generates an rndc.conf file for the rndc utility.
chkconfig sshd off
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.
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.