Archive for the ‘Interview’ Category


Real Time Based Questions in Redhat Linux

  1. Linux Boot Process
  2. Linux Partition
  3. Linux File System Hierarchy
  4. Important Configuration files Linux
  5. /Proc
  6. Server configuration file s and Packages
  7. Monitoring Commands
  8. Port Numbers In Linux

9.Linux Logs

Linux Boot Process (Startup Sequence)

linux-boot-process

Linux Partition for OS installation

/

/boot

Swap

/home

/var

/etc

Linux Directory Structure/ File System

filesystem-structure

 

Linux Server and Port number

20 – FTP Data (For transferring FTP data)

21 – FTP Control (For starting FTP connection)

22 – SSH(For secure remote administration which uses SSL to encrypt the transmission)

23 – Telnet (For insecure remote administration

25 – SMTP(Mail Transfer Agent for e-mail server such as SEND mail)

53 – DNS(Special service which uses both TCP and UDP)

68 – DHCP

69 – TFTP(Trivial file transfer protocol uses udp protocol for connection less transmission of data)

80 – HTTP/WWW (apache)

88 – Kerberos

110 – POP3(Mail delivery Agent)

123 – NTP(Network time protocol used for time syncing uses UDP protocol)

137 – NetBIOS(nmbd)

139 – SMB-Samba(smbd)

143 – IMAP

995 – POP3s

161 – SNMP(For network monitoring)

389 – LDAP(For centralized administration)

443 – HTTPS(HTTP+SSL for secure web access)

636 – ldaps(both tcp and udp)

873 – rsync

989 – FTPS-data

990 – FTPS

993 – IMAPS

2049 – NFS(nfsd, rpc.nfsd, rpc, portmap) 2401 – CVS server

3306 – MySql

 

1. /proc Directories with names as numbers

Do a ls -l /proc, and you’ll see lot of directories with just numbers. These numbers represents the process ids, the files inside this numbered directory corresponds to the process with that particular PID.

Following are the important files located under each numbered directory (for each process):

  • cmdline – command line of the command.
  • environ – environment variables.
  • fd – Contains the file descriptors which is linked to the appropriate files.
  • limits – Contains the information about the specific limits to the process.
  • mounts – mount related information

Following are the important links under each numbered directory (for each process):

  • cwd – Link to current working directory of the process.
  • exe – Link to executable of the process.
  • root – Link to the root directory of the process.

2. /proc Files about the system information

Following are some files which are available under /proc, that contains system information such as cpuinfo, meminfo, loadavg.

/proc/cpuinfo – information about CPU,

  • /proc/meminfo – information about memory,
  • /proc/loadvg – load average,
  • /proc/partitions – partition related information,
  • /proc/version – linux version

Some Linux commands read the information from this /proc files and displays it. For example, free command, reads the memory information from /proc/meminfo file, formats it, and displays it.

To learn more about the individual /proc files, do “man 5 FILENAME”.

  • /proc/cmdline – Kernel command line
  • /proc/cpuinfo – Information about the processors.
  • /proc/devices – List of device drivers configured into the currently running kernel.
  • /proc/dma – Shows which DMA channels are being used at the moment.
  • /proc/fb – Frame Buffer devices.
  • /proc/filesystems – File systems supported by the kernel.
  • /proc/interrupts – Number of interrupts per IRQ on architecture.
  • /proc/iomem – This file shows the current map of the system’s memory for its various devices
  • /proc/ioports – provides a list of currently registered port regions used for input or output communication with a device
  • /proc/loadavg – Contains load average of the system
    The first three columns measure CPU utilization of the last 1, 5, and 10 minute periods.
    The fourth column shows the number of currently running processes and the total number of processes.
    The last column displays the last process ID used.
  • /proc/locks – Displays the files currently locked by the kernel
    Sample line:
    1: POSIX ADVISORY WRITE 14375 08:03:114727 0 EOF
  • /proc/meminfo – Current utilization of primary memory on the system
  • /proc/misc – This file lists miscellaneous drivers registered on the miscellaneous major device, which is number 10
  • /proc/modules – Displays a list of all modules that have been loaded by the system
  • /proc/mounts – This file provides a quick list of all mounts in use by the system
  • /proc/partitions – Very detailed information on the various partitions currently available to the system
  • /proc/pci – Full listing of every PCI device on your system
  • /proc/stat – Keeps track of a variety of different statistics about the system since it was last restarted
  • /proc/swap – Measures swap space and its utilization
  • /proc/uptime – Contains information about uptime of the system
  • /proc/version – Version of the Linux kernel, gcc, name of the Linux flavor installed.

Linux Log Files

 

  1. /var/log/messages – Contains global system messages, including the messages that are logged during system startup. There are several things that are logged in /var/log/messages including mail, cron, daemon, kern, auth, etc.
  1. /var/log/dmesg – Contains kernel ring buffer information. When the system boots up, it prints number of messages on the screen that displays information about the hardware devices that the kernel detects during boot process. These messages are available in kernel ring buffer and whenever the new message comes the old message gets overwritten. You can also view the content of this file using the dmesg command.
  1. /var/log/auth.log – Contains system authorization information, including user logins and authentication machinsm that were used.
  1. /var/log/boot.log – Contains information that are logged when the system boots
  1. /var/log/daemon.log – Contains information logged by the various background daemons that runs on the system
  1. /var/log/dpkg.log – Contains information that are logged when a package is installed or removed using dpkg command
  2. /var/log/kern.log – Contains information logged by the kernel. Helpful for you to troubleshoot a custom-built kernel.
  1. /var/log/lastlog – Displays the recent login information for all the users. This is not an ascii file. You should use lastlog command to view the content of this file.
  1. /var/log/maillog /var/log/mail.log – Contains the log information from the mail server that is running on the system. For example, sendmail logs information about all the sent items to this file
  1. /var/log/user.log – Contains information about all user level logs
  1. /var/log/Xorg.x.log – Log messages from the X
  1. /var/log/alternatives.log – Information by the update-alternatives are logged into this log file. On Ubuntu, update-alternatives maintains symbolic links determining default commands.
  1. /var/log/btmp – This file contains information about failed login attemps. Use the last command to view the btmp file. For example, “last -f /var/log/btmp | more”
  1. /var/log/cups – All printer and printing related log messages

 

  1. /var/log/anaconda.log – When you install Linux, all installation related messages are stored in this log file

 

  1. /var/log/yum.log – Contains information that are logged when a package is installed using yum
  1. /var/log/cron – Whenever cron daemon (or anacron) starts a cron job, it logs the information about the cron job in this file
  1. /var/log/secure – Contains information related to authentication and authorization privileges. For example, sshd logs all the messages here, including unsuccessful login

/var/log/wtmp or /var/log/utmp – Contains login records. Using wtmp you can find out who is logged into the system. who command uses this file to display the information.

  1. /var/log/faillog – Contains user failed login attemps. Use faillog command to display the content of this file.

Apart from the above log files, /var/log directory may also contain the following sub-directories depending on the application that is running on your system.

  • /var/log/httpd/ (or) /var/log/apache2 – Contains the apache web server access_log and error_log
  • /var/log/lighttpd/ – Contains light HTTPD access_log and error_log
  • /var/log/conman/ – Log files for ConMan client. conman connects remote consoles that are managed by conmand daemon.
  • /var/log/mail/ – This subdirectory contains additional logs from your mail server. For example, sendmail stores the collected mail statistics in /var/log/mail/statistics file
  • /var/log/prelink/ – prelink program modifies shared libraries and linked binaries to speed up the startup process. /var/log/prelink/prelink.log contains the information about the .so file that was modified by the prelink.
  • /var/log/audit/ – Contains logs information stored by the Linux audit daemon (auditd).
  • /var/log/setroubleshoot/ – SELinux uses setroubleshootd (SE Trouble Shoot Daemon) to notify about issues in the security context of files, and logs those information in this log file.
  • /var/log/samba/ – Contains log information stored by samba, which is used to connect Windows to Linux.
  • /var/log/sa/ – Contains the daily sar files that are collected by the sysstat package.
  • /var/log/sssd/ – Use by system security services daemon that manage access to remote directories and authentication mechanisms.

Trouble shooting In Linux

Getting ram information

cat /proc/meminfo

cat /proc/meminfo | head -n 1

Another fun thing to do with ram is actually open it up and take a peek. This next command will show you all the string (plain text) values in ram.

sudo dd if=/dev/mem | cat | strings

Getting cpu info

Sometimes in troubleshooting we want to know what processor we are dealing with along with how much cpu is currently being used by our OS and programs. We can do this with these two commands.

cat /proc/cpuinfo

top

Check the temperature of your CPU

Keeping a computer within a safe temperature is the key to maintaining a stable system.e

List PCI and USB devices

To list all the PCI devices in your system issues the following command:

lspci

For USB use:

lsusb

Check out how much hard drive space is left

df -h

See what hard drives are currently detected

It is often times helpful to know what hard drives are connected to a system and what name was given them in the Linux directory. This info allows us to mount the hard drive and manipulate it.

sudo fdisk -l

Installed Programs

Packages

Ever want to find all the packages that are installed on your system? You can find all the packages and also find out why they are on your system. You can even determine what packages depend on them if any.

Find all installed packages

dpkg –get-selections | less

Find out why a packages is installed and what depends on it

aptitude why packagename

Find out where the package stores all of its files

dpkg -L packagename

Kill a process

ps -A | grep ProgramName

kill 7207

Miscellaneous

Go to a terminal

Ctrl + Alt + f3

return with, Ctrl + Alt + f7

Show all network connections

There are many great network scanners and assessment tools available for Linux but netstat is a very easy to use often a first step in troubleshooting network issues. We will leave the rest of the network tools for a later article as there is so much to cover.

netstat

List all files that are currently open on the system

This command will allow you to see all the files that are currently open on your system. Limiting the directory or coupling this command with grep is often useful for finding files that are still open restricting the ability to unmount a device. Lsof will also ouput the process id or PID. You can then kill the process using the kill command above.

lsof

Keep an eye on something for awhile

The watch command will repeat a command at a set interval (default 2 seconds) and output the response. This is useful for watching directories that change, watching hard drives fill up when a lot of data is being transfered, or using it with lsusb to watch for USB devices being plugged in.

watch ls

watch df -h

Find where a binary is stored and its libraries

Often times when running a cron command you want to include the absolute path to the command. Sometimes I run scheduled PHP tasks. This can be acomplished by using the ‘whereis‘ command.

whereis php5

Logs

See if you have kernel boot issues

dmesg | less

For more logs just cd into the /var/log directory and start using, catlesstailgrepfind or any other tool to view and search.

Linux Network troubleshooting step by step

Here we go into the topic.

1- First check that your interface (Network adapter ) is enabled or not using:         ifconfig

2- To make sure there is no internal problem.

     ping to the loop back address  ping 127.0.0.1

   if there is no response  service network restart if same repeats check network settings again.

3- check cable problem from ethtool eth0

if everything is fine then last line will show

 
                Link detected: yes
 
    
     if link is not detected plug it or change the cable according to need and problem
4-check the gateway settings in 
 
/etc/network    and
 /etc/sysconfig/network-scripts/ifcfg-eth0

And check DNS settings in

 /etc/resolv.conf 
 
system-config-network 

netstat

route 

service iptables stop

( only disable the firewall for testing and dont forget to turn it on)

check boot messages if eth card is detected at boot time or not

cat /var/log/dmesg | grep -i eth0

or

dmesg | grep -i eth0

to check table of network interfaces

netstat -i

for more advanced troubleshooting

lspci | less

or
lspci | grep ethernet

to check all PCI buses and devices connected to them

These are enough to troubleshoot if still problem persist try installing drivers , check kernel related problems , check is there any need to recompile the kernel etc

Advertisements

Linux Administrator Interview Questions

 

Which user authentication methods can be used with SLES 10? (Choose 4.)

 

A. NIS

B. WEP

C. SSH

D. PAM

E. LDAP

F. Handshake

G. Windows Domain

H. Local (/etc/passwd)

 

Answer: A,E,G,H

 

Which statements about partitions are correct? (Choose 3.)

 

A. Extended partitions can be subdivided into logical partitions.

B. A primary partition consists of a continuous range of cylinders.

C. Logical partitions do not require entries in the main partition table.

D. If you use only primary partitions, you are limited to eight partitions per disk.

E. SUSE Linux Enterprise Server 10 can only be installed on a primary partition.

F. To install more than one operating system on a partition, the partition has to include the entire

cylinder range.

 

Answer: A,B,C

 

You want to copy the master boot record, the partition table, and the 2 magic bytes at the

beginning of /dev/had to a file so you can restore it later. Which command accomplishes this?

 

A. dd if=/dev/hda of=mbr bs=512 count=1

B. dd if=mbr of=/dev/hda bs=512 count=1

C. dd of=/dev/zero if=/dev/hda bs=512 count=1

D. dd if=/dev/urandom of=/dev/hda bs=512 count=1

tualTests.com

Answer: A

 

The /etc/sysconfig/network/ifcfg-eth-id-macaddress configuration file contains a BOOTPRO option. Which are possible values of BOOTPROTO?

A. static or dhcp

B. master or slave

C. onboot, ifpluged, or manual

 

Answer: A

From command mode in vi, what do you have to do to enter text?

 

A. Press e

B. Press i

C. Press k

D. Press w

 

Answer: B

 

Which statement about symmetric encryption is correct?

 

A. The same key is used for encryption and decryption.

B. Symmetric keys are generally longer than asymmetric keys.

C. Asymmetric encryption is generally faster than symmetric encryption.

D. A public key and a private key are needed for symmetric encryption/decryption.

 

Answer: A

 

After the partitions are checked and the root file system is mounted, the /sbin/init command is executed. Which process ID is assigned to /sbin/init?

 

A. 0

B. 1

C. 3

D. 100

E. 1000

F. Depends

 

Answer: B

 

When you connect to an ssh server with your ssh client, the public key of the server is compared  to the keys stored in a file on the client computer. Which file is this?

 

A. ~/.ssh/id_dsa.pub

B. ~/.ssh/id_rsa.pub

C. ~/.ssh/known_hosts

D. ~/.ssh/authorized_keys

 

Answer: C

 

You want to install the xyz-software-1.2.3-5.i586.rpm package, but only if a previous version is already installed. Which command will do this?

 

A. rpm -ivh xyz-software-1.2.3-5.i586.rpm

B. rpm -evh xyz-software-1.2.3-5.i586.rpm

C. rpm -Fvh xyz-software-1.2.3-5.i586.rpm

D. rpm -Uvh xyz-software-1.2.3-5.i586.rpm

ActualTests.com

Answer: C

 

Which commands can be used if you do not find the desired information in a manual page, or find no manual page at all for a program?

 

A. sos program

B. info program

C. help program

D. wiki program

 

Answer: B

 

Which statements about PAM are correct? (Choose 3.)

 

A. To enable authentication with PAM, you need a smart cart reader.

B. Each line in a PAM configuration file contains 6 columns plus optional arguments.

C. Configuration files of PAM modules can be found in /etc/pam.d/ and /etc/security/.

D. After the PAM configuration has been adjusted for an application, this application can be usedby SSH.

E. The /etc/pam.d/other file contains a default configuration if no application-specific file is found in/etc/pam.d/.

F. PAM creates a software level with defined interfaces between applications and the currentAuthentication mechanism.

 

Answer: C,E,F

 

What is the difference between the /dev/st0 and /dev/nst0 devices?

 

A. /dev/st0 is the first SCSI CD burner; /dev/nst0 refers to the CDROM drive.

B. /dev/st0 is the first tape drive; /dev/nst0 refers to the same tape drive in non-rewinding mode.

C. /dev/st0 is the first serial console; /dev/nst0 refers to the same serial console as a block device.

D. /dev/st0 is the first SCSI hard drive; /dev/nst0 refers to the same SCSI hard drive in read-only

mode.

 

Answer: B

 

How do you create a file called destination containing the same ACLs currently set for the file  called source?

A. getfacl source > destination

B. getfacl -c source destination

C. getfacl source | cp destination

D. getfacl -x source > destination

 

Answer: A

 

From the command line, which command would you use to print the document.ps file on the laser printer?

 

A. lp -d laser document.ps

B. lpr -p laser document.ps

C. lpq -p laser document.ps

D. print -p laser document.ps

 

Answer: A

 

You want to find out if files from the wget package were altered since they were installed. Which command will give you this information?

 

A. rpm -V wget

B. rpm -v wget

C. rpm -F wget

D. rpm -qf wget

 

Answer: A

 

In which file is the name resolution configured?

 

A. /etc/dns.conf

B. /etc/resolv.conf

C. /etc/HOSTNAME

D. /etc/nameservers

E. /etc/sysconfig/network/dns

 

Answer: B

 

Which command can you use to set up limits for failed logins?

 

A. w

B. who

C. last

D. faillog

E. lastlog

 

Answer: D

 

 

 

Which file system type supports ACLs without a special mount option?

 

A. ext2

B. ext3

C. XFS

D. ReiserFS

 

Answer: C

 

Which statement about the /sbin/ldconfig command is correct?

 

A. The ldconfig command is used to link directories.

B. The ldconfig command is used to configure an LDAP connection.

C. The ldconfig command is used to update the software library cache.

D. The ldconfig command is used to show dynamic libraries needed by a program.

 

Answer: C

 

Which command displays information about your hard drive and lets you manage certain hard drive parameters?

A. siga

B. sitar

C. fdisk

D. lspci

E. iostat

F. hwinfo

G. hdparm

 

Answer: G

 

Which file can be used to send a message to users logging in on a text console?

 

A. /etc/net

B. /etc/motd

C. /etc/message

D. /var/log/messages

 

Answer: B

 

What is the correct syntax for mounting the second partition of the first SCSI hard disk?

 

A. mount /mnt /dev/hda2

B. mount /dev/hda2 /mnt

C. mount /dev/sdb1 /mnt

D. mount /mnt /dev/sdb1

E. mount /dev/sda2 /mnt

F. mount /mnt /dev/sda2

 

Answer: E

 

Using the rsync command, you want to mirror the directories, including any hidden files and directories within /home (not the /home directory itself) to the /backup directory. Which command accomplishes this?

 

A. rsync -a /home /backup

B. rsync -a /home/. /backup

C. rsync -a /home/* /backup

D. rsync -a /home/? /backup

 

Answer: B

 

 

You want to add user tux to the southpole group without changing his primary group membership.Which command do you use for this purpose?

 

A. useradd -g southpole tux

B. usermod -g southpole tux

C. groupadd -A tux southpole

D. groupmod -A tux southpole

 

Answer 😀

 

Which file contains information about which user was last logged in, where the user logged in, and how long the user was logged in?

A. /var/log/login

B. /var/log/lastlog

C. /var/log/access

D. /var/log/messages

E. There is no log file containing this information

 

Answer: B

 

You entered your quota information in /etc/fstab. What do you have to do next?

ctualTests.com

A. Generate a quota report.

B. Initialize the quota system.

C. Configure limits for users and groups.

D. Remount the file system for the quotas to be defined.

 

Answer: D

 

While the printers seem physically okay, you are encountering problems with CUPS. What is the best place to start looking for hints on what is wrong?

 

A. In the output of dmesg

B. In the /var/log/boot.msg file

C. In the /var/log/messages file

D. In the /var/log/cups/error_log file

 

Answer: D

 

What does the following command do? tar -czvf /tmp/backup.tgz /etc/HOSTNAME

 

A. It extracts the /etc/HOSTNAME file from the /tmp/backup.tgz archive.

B. It includes the /etc/HOSTNAME file in the newly created /tmp/backup.tgz archive.

C. It produces an error message because the options are in the wrong sequence.

D. It displays a line similar to the following, but otherwise does nothing: -rw-r–r– root/root 23 2005-

03-11 14:20 etc/HOSTNAME

 

Answer: B

 

You have a text file that contains empty lines. Using grep and regular expressions, which

command displays the file without the empty lines?

ActualTests.com

A. grep ^$ file

B. grep [\ ] file

C. grep -v ^$ file

D. grep -v #$ file

 

Answer: C

 

Which statement regarding symbolic links is true? (Choose 2.)

 

A. A symbolic link can point to a file on a different file system.

B. A symbolic link and the file it points to share the same inode.

C. If you delete the symbolic link, the original file is deleted as well.

D. If you delete the original file, the symbolic link points to a non-existing file.

E. With a symbolic link, you cannot see directly that it is a link.

 

Answer: A,D

 

Which statement about the sudo command is correct?

 

A. You can edit the sudo configuration file /etc/sudo.conf directly with vi.

B. You can edit the su configuration file /etc/su.conf with the sudo command.

C. You can edit the sudo configuration file /etc/sudoers with the visudo command.

D. You can edit the sudo configuration file /etc/visudo with the sudoers command.

 

Answer: C

 

What is the name of the file containing the initramfs?

 

A. /

B. /boot/initrd

C. /boot/ramfs

D. /sbin/vmram

E. /boot/vmram

F. /sbin/linuxramfs

 

Answer: B

 

You would like to run command2 only if command1 did not complete successfully.

Which command accomplishes this task?

 

A. command1 ;; command2

B. command1 || command2

C. command1 >> command2

D. command1 && command2

 

Answer: B

 

You want to secure a POP3 connection to a server that does not support SSL. While you do not have ssh access to the POP3 server itself, you at least have SSH access to a server near the POP3 server. Given the following information:

POP3 server: pop3.digitalairlines.com

SSH server: ssh.digitalairlines.com

Your host: da10.digitalairlines.com

POP3 port: 110

Local port: 11110

Which command will forward connections from the local port 11110 to port 110 of the POP3

server, using a secure tunnel between your host and the SSH server?

 

A. ssh -L 11110:ssh.digitalairlines.com:110 geeko@pop3.digitalairlines.com

B. ssh -L 110:ssh.digitalairlines.com:11110 geeko@pop3.digitalairlines.com

C. ssh -L 11110:pop3.digitalairlines.com:110 geeko@ssh.digitalairlines.com

D. ssh -L 110:pop3.digitalairlines.com:11110 geeko@ssh.digitalairlines.com

 

Answer: C

 

Which command is used to enter or change the quota for user tux?

A. quotacheck

B. repquota tux

C. edquota -u tux

D. edquota -g tux

E. /sbin/quotaon tux

 

Answer: C

 

Which statements about the Linux boot process are correct? (Choose 3.)

 

A. The BIOS starts the kernel.

B. The initrd decompresses itself.

C. The kernel looks for and mounts the initrd.

D. The boot manager starts the init process.

E. linuxrc loads the modules to mount the root file system.

F. The boot manager loads the kernel and initrd into the memory.

 

Answer: C,E,F

 

Which group name is stored in /etc/passwd?

 

A. Primary group

B. Effective group

C. Secondary group

D. No group name is stored there.

 

Answer: A

 

The GRUB configuration file (/boot/grub/menu.lst) has a global section followed by sections for each operating system. Which options do you have to specify for each Linux operating system?(Choose 3.)

A. title

B. color

C. initrd

D. kernel

E. timeout

F. gfxmenu

G. message

 

Answer: A,C,D

 

You want to use the ip command to set a new address for your network device eth0. It is a

standard class C network. The broadcast address and network route should be set accordingly.

Which command is correct?

 

A. ip address set 192.168.0.10/24 dev eth0

B. ip address add 192.168.0.10/24 dev eth0

C. ip addr add 192.168.0.10/24 dev eth0 brd +

D. ip addr add eth0 192.168.0.10/24 eth0 broadcast 192.168.255.255

 

Answer: C

ActualTests.com

Which command can you use to generate an MD5-encrypted password for GRUB?

A. genkey –md5

B. grubpass -md5

C. grub-md5-crypt

D. passwd -c –md5

 

Answer: C

 

The /backup/snapshot was changed to the /backup/backup_monday.tgz archive. Which command

will now write new or modified files below /home?

 

A. tar -czf -g /backup/snapshot /backup/backup_monday.tgz /home

B. tar -tz -g /backup/snapshot -f /backup/backup_monday.tgz /home

C. tar -cz -g /backup/snapshot -f /backup/backup_monday.tgz /home

D. tar -cz -newer /backup/snapshot -f /backup/backup_monday.tgz /home

 

Answer: C

 

Which protocol is used to send messages by the ping command?

A. NTP

B. FTP

C. TCP

D. ICMP

E. HTTP

F. LDAP

 

Answer: D

ActualTests.com

Which parts can be combined in the syslog-ng configuration file (/etc/syslog-ng/syslog-ng.conf) to specify what information is logged? (Choose 3.)

 

A. Alerts

B. Users

C. Filters

D. Sources

E. Log Paths

F. Destinations

G. Date and Time

 

Answer: C,D,F

 

What is the output of the echo ‘$HOME’ command when user geeko (home directory

/home/geeko) enters it at the bash shell prompt?

 

A. geeko

B. $HOME

C. /home/geeko

D. $HOME: No such file or directory

 

Answer: B

Which statement about the primary (default) group of a user is correct?

 

A. The primary group membership of a user is defined in the /etc/group file.

B. The primary group membership of a user is defined in the /etc/shadow file.

C. The primary group membership of a user is defined in the /etc/passwd file.

D. The primary group membership of a user is defined in the /etc/gpasswd file.

 

Answer: C

 

ActualTests.com

In a terminal window, which command shows you the groups you are a member of?

 

A. id

B. gid

C. who

D. whoami

 

Answer: A

 

How large is an inode?

A. 256 bits

B. 64 Kbytes

C. 128 bytes

D. 1 Mbyte

 

Answer: C

 

You want to create the new user account tux with the password penguin (password hash:

TvqBFhQWgeSho) and a default home directory. Which command can be used to create the

account with the above parameters?

 

A. useradd -m -p “penguin” tux

B. echo penguin | useradd -m -p – tux

C. useradd -m -p “TvqBFhQWgeSho” tux

D. echo -e “penguin\npenguin” | passwd tux ; useradd -m tux

Answer: C

 

In a terminal window, which command displays the name of the directory you are currently in?

ActualTests.com

A. dir

B. pwd

C. where

D. current-dir

 

Answer: B

 

Which range of User IDs is used for normal (unprivileged) users on SUSE Linux Enterprise Server 10?

 

A. 0-100

B. 101-499

C. 500-999

D. 1000 and above

 

Answer: D

 

Where can you set global shell environment variables for all users independent of their shell?

 

A. /etc/profile

B. /etc/profile.all

C. /etc/bash.local

D. /etc/bash.bashrc

 

Answer: A

 

You have set the following permissions on a test directory: rwxrwxrwx. Which statement about files

in the test directory is correct?

 

A. Only root can delete files in the test directory.

B. Only root or the owner of a file can delete files in the test directory.

C. A file created in that directory has the same owner as the owner of the test directory.

D. A file created in that directory has the same owning group as the owning group of the test directory.

 

Answer: D

 

Which key combination can you use to stop a process that runs in the foreground?

A. Ctrl +X

B. Ctrl +Z

C. Ctrl + Alt + X

D. Ctrl + Backspace

 

Answer: B

I want to redirect both output and error messages of the find command to the find-output file Which command accomplishes this task?

A. find /etc -name “*conf” 2>&find-output

B. find /etc -name “*conf” 2<&1 > find-output

C. find /etc -name “*conf” > find-output 2>&1

D. find /etc -name “*conf” > find-output 2>find-output

 

Answer: C

 

Which are benefits of using LVM? (Choose 4.)

A. You can increase data security.

B. You can create extremely large logical volumes.

C. You can add logical volumes in a running system.

D. You can add hard disks to a volume group in a running system.

E. You can reduce the size of a logical volume without unmounting it.

F. The snapshot feature allows consistent backups in a running system.

 

Answer: B,C,D,F

 

Within less, how do you search for a string downwards from where the cursor is positioned?

A. \string

B. ?string

C. /string

D. =string

 

Answer: C

 

In the bash shell, which command can be used to create a MY_NAME variable containing the value Joe?

A. MY_NAME=Joe

B. MY_NAME = Joe

C. echo Joe > MY_NAME

D. export MY_NAME = Joe

 

Answer: A

 

Which are journaling file systems? (Choose 3.)

A. XFS

B. ext2

C. ext3

D. VFAT

E. minix

F. VFAT32

G. ReiserFS

 

Answer: A,C,G

 

What is the type command used for?

A. type is used to print text to a teletypewriter.

B. type displays the type of terminal (tty1, tty2) you are logged in to.

C. type determines the type of a command (shell builtin, alias, file on hard disk).

D. type is used to determine the type of processor used (32-bit, 64-bit, Power).

 

Answer: C

 

What is the correct order of steps to change the partition table using fdisk?

 

A. You can’t use fdisk to change a partition table.

B. Start fdisk > Change the partition table > Write the partition table to hard disk > Exit fdisk >

Reboot.

C. Start fdisk > Change the partition table > Write the partition table to hard disk > Exit fdisk >

Load the partition table from the boot prompt.

D. Start fdisk > Change the partition table > Write the partition table to floppy disk or USB stick >

Exit fdisk > Boot from floppy disk or USB stick.

 

Answer: B

 

You want to redirect the output of the ls command to the ls-output file which already exists. The

output should be appended to the file; it should not overwrite the existing content. Which

command accomplishes this task?

 

A. ls > ls-output

B. ls : ls-output

C. ls >> ls-output

D. ls && ls-output

 

Answer: C

 

You have a /tmp/data directory containing the files .file, file1, and file2. You want to delete the directory and its content. In a terminal window, which command accomplishes this?

A. rm /tmp/data/

B. rm -r /tmp/data/

C. rmdir /tmp/data/

D. deldir /tmp/data/

 

Answer: B

 

Which statement about a CUPS Using Broadcasting configuration is correct?

 

A. Only local printing is possible.

B. You can print to both local and network printers.

C. Only one queue on one print server can be used for printing.

D. All queues on only one CUPS server are available for printing.

 

Answer: B

 

As system administrator root, you use the lpoptions command to change printer options, such as the page size. To which file are these options saved?

ActualTests.com

A. ~/.bashrc

B. ~/.lpoptions

C. /etc/cups/lpoptions

D. /etc/sysconfig/cups

 

Answer: C

 

You want to delete a certain print job from the laser print queue. Using the lpq command, you determined the job number of this job as 1234. Which command lets you delete that job?

A. lpr -P laser 1234

B. lprm -P laser 1234

C. lpremove -P laser 1234

D. lpadmin -d laser -r 1234

 

Answer: B

 

Which command is suitable for displaying the CPU load as a percentage?

A. w

B. top

C. nice

D. uptime

 

Answer: B

 

What action does the jobs command perform?

 

A. Lists all scheduled cron jobs

B. Lists all mail items in the mail queue

C. Lists the content of the shell’s job control

D. Lists all print jobs in the print queue.

 

Answer: C

 

Using the nice command, what is the highest priority root can assign to a process?

 

A. -20

B. -19

C. 0

D. 19

E. 20

F. 99

 

Answer: A

 

To preserve the command history even when the shell is closed, the history is written to a file in the user’s home directory. Which file holds the history information of the bash shell?

 

A. bash_history

B. .bash_history

C. ?bash_history

D. $bash_history

 

Answer: B

 

You want to disable the network device eth0. Which command can you use?

 

A. ifconfig halt eth0

B. ipconfig eth0 halt

C. ip link set eth0 down

D. ip param set eth0 halt

 

Answer: C

 

You wonder which installed RPM package the /etc/exports file belongs to. Which command will

give you the desired information?

 

A. rpm -f /etc/exports

B. rpm -qf /etc/exports

C. rpm -ql /etc/exports

D. rpm –provides /etc/exports

 

Answer: B

 

Which is the main configuration file for logrotate?


A.
/etc/logrotate

B. /etc/logr.conf

C. /etc/cron/logrotate

D. /etc/logrotate.conf

 

Answer: D

 

You want to delete all data on the second hard drive (/dev/hdb). Which command accomplishes this?

A. rm /dev/hdb

B. dd if=/dev/zero of=/dev/hdb bs=100k

C. dd of=/dev/zero if=/dev/hdb bs=100k

D. dd if=/dev/zero of=/dev/hdb count=1 bs=1024

 

Answer: B

 

You want to copy the mytext file from your computer to the /tmp/ directory on the remote computer  da20. digitalairlines.com. Which command would you use to accomplish this?

 

A. ssh mytext da20.digitalairlines.com:/tmp

B. scp da20.digitalairlines.com:/tmp mytext

C. scp mytext da20.digitalairlines.com:/tmp

D. sftp mytext da20.digitalairlines.com:/tmp

 

Answer: C

 

Which statement about a differential backup is correct?

 

A. The use of differential backups is limited to backups on tape roboters.

B. To restore a differential backup, you need the last differential backup only.

C. To restore a differential backup, you need the last full backup and the last differential backup

that was made since the last full backup.

D. The amount of data that needs to be backed up with each differential backup depends only on

the amount of data changed since the last differential backup.

 

Answer: C

 

Which statement about the Set User ID bit on executable files is correct?

 

A. The SUID bit has no security implications.

B. The SUID bit on executables has no effect; it is only relevant when set on directories.

C. The SUID bit makes it more difficult to exploit any potential vulnerabilities in the program.

D. The SUID should only be set when really needed and only on applications that are well tested.

 

Answer: D

 

You are viewing the manual page of crontab, but it does not contain the information you are looking for. You suspect there is another crontab manual page. Which command could you use to find out if another crontab manual page exists? (Choose 2.)

 

A. man a crontab

B. whatis crontab

C. man -k crontab

D. man –next crontab

E. man –showall crontab

 

Answer: B,C

 

You want to know which files are contained in the hugin-0.6.1-2.2.i586.rpm RPM package, which has not yet been installed. Which command will give you this information?

 

A. rpm -f hugin-0.6.1-2.2.i586.rpm

B. rpm -qpf hugin-0.6.1-2.2.i586.rpm

C. rpm -qpl hugin-0.6.1-2.2.i586.rpm

D. rpm –provides hugin-0.6.1-2.2.i586.rpm

 

Answer: C

 

You created a script (/root/bin/backup.sh) that backs up your files when executed. Using cron, you want to execute this script once every Saturday at 3:00 pm. Which line would you have to enter after invoking crontab – e in a terminal window?

 

A. 15 0 * * 6 /root/bin/backup.sh

B. 0 15 * * 6 /root/bin/backup.sh

C. 0 15 * 6 * /root/bin/backup.sh

D. 15 0 * * 6 root /root/bin/backup.sh

 

Answer: B

 

While in insert mode, how do you save a file and close vi?

 

A. Press Esc and :q

B. Press Esc and :w

C. Press Esc and :wq

D. Press Esc and :zz

Answer C

 

You want to install the ethereal RPM package that is available on the SUSE Linux Enterprise

Server 10 installation media. Which command installs the ethereal package, and resolves

dependencies as needed?

 

A. rpm -i ethereal

B. yast -i ethereal

C. yast -l ethereal

D. rpm -U ethereal

 

Answer: B

 

Which command can be used to view the inode assigned to a filename?

 

A. ls -i

B. fsck -h -i

C. inode –list

D. cat /proc/inodes

 

Answer: A

 

Which lists of wireless networks are kept by NetworkManager?

 

A. Preferred list and avoid list

B. User list and encryption list

C. Trusted list and preferred list

D. Trusted list and untrusted list

 

Answer: C

 

What is the effect of selecting the option “Enable IP Forwarding” in the routing configuration in YaST?

 

A. IP packets that do have this host as their destination are routed to another host.

B. IP packets that do not have this host as their destination are filtered according to the firewall

rules.

C. IP packets that do have this host as their destination are dropped to protect the host from

attacks.

D. IP packets that do not have this host as their destination are transferred from one network

connected to the host to another network connected to this host, according to the routing table.

 

Answer: D

 

You want to boot your system to runlevel 3. Which option do you have to enter at the GRUB boot manager dialog?

 

A. 3

B. init=3

C. boot=3

D. runlevel=3

 

Answer: A

 

You would like to run command1 and then command2, whether or not command1 completed

successfully. Which command accomplishes this task?

 

A. command1 | command2

B. command1 ; command2

C. command1 > command2

D. command1 & command2

 

Answer: B

 

You want to find out which jobs are currently queued in the laser print queue on your CUPS print

server. Which command displays the information you need?

 

A. lpstat -t

B. lp -P laser

C. lpq -P laser

D. lpadmin -P laser

 

Answer: C

 

In which file is the host name of a Linux computer configured? (Hint: You do not need to include the entire path.)

 

Answer: /etc/HOSTNAME

 

 

You want to view the status (locked, valid password, etc.) of the account tux.

Which command displays the desired information?

 

A. passwd -L tux

B. passwd -v tux

C. passwd -p tux

D. passwd -S tux

 

Answer: D

 

In which file are global configurations for users who use bash as their login shell set?

 

A. /etc/bashrc

B. /etc/bash.cf

C. /etc/bash.conf

D. /etc/bash.bashrc

 

Answer: D

 

Which command displays the value stored in the $MYVAR variable?

 

A. less MYVAR

B. cat $MYVAR

C. echo MYVAR

D. echo $MYVAR

 

Answer: D

 

Which file contains the configuration information of the print queues available on your CUPS server?

 

A. The /etc/printcap file

B. The /etc/sysconfig/cups file

C. The /etc/cups/cups.conf file

D. The /etc/cups/printers.conf file

 

Answer: D

 

How can you list the ACLs (if there are any) of a file test?

 

A. ls -l test

B. lsacl test

C. getfacl test

D. ls -l –acl test

 

Answer: C

 

Routes to the directly connected network are automatically set up when a device is started. All other routes are saved in which configuration file?

 

A. /etc/route

B. /etc/routes

C. /etc/routes.conf

D. /etc/network/routes

E. /etc/sysconfig/routes

F. /etc/sysconfig/network/routes

 

Answer: F

 

What information do you need to set up an LDAP client? (Choose 4.)

 

A. LDAP version

B. LDAP base DN

C. Kind of encryption

D. Synchronization frequency

E. Address of the LDAP server

F. File name of the LDAP database

 

Answer: A,B,C,E

 

What is the minimum number of partitions required by a SLES 10 system?

 

A. None

B. 1

C. 2

D. 4

 

Answer: C

 

What is the purpose of the ssh-agent command?

 

A. ssh-agent is a program that helps configure the ssh daemon.

B. ssh-agent is used to fetch public keys from machines within your network.

C. ssh-agent is used to avoid typing the passphrase for your key on each login.

D. ssh-agent is a program that checks for machines in the network that have an ssh daemon

running.

 

Answer: C

 

Using the nice command, what is the highest priority a normal user can assign to a process?

A. -20

B. -19

C. 0

D. 19

E. 20

F. 99

 

Answer: C

Which command can you use to create a Reiser file system on the sda6 partition? (Choose 2.)

 

A. mkreiserfs /dev/sda6

B. fdisk.reiserfs /dev/sda6

C. make.reiserfs /dev/sda6

D. fdisk -t reiserfs /dev/sda6

E. mkfs -t reiserfs /dev/sda6

 

Answer: A,E

 

You have limited access to the /admin directory of the web interface of your CUPS server with the following statement in /etc/cups/cupsd.conf:

<Location /admin>

AuthType BasicDigest

AuthClass Group

AuthGroupName sys

Order Deny,Allow

Deny From All

Allow From 127.0.0.1

</Location>

To allow the cupsadmin user to access the /admin directory when connecting from localhost, how

do you create the cupsadmin user and set his password?

 

A. passwd cupsadmin

B. lppasswd cupsadmin

C. passwd –cups cupsadmin

D. lppasswd -a cupsadmin -g sys

 

Answer: D

 

i have a test directory with the following permissions: rwx—— You want to change the

permissions to the following values: r-xr-xr-x. Which command accomplishes this?

 

A. chmod 777 test

B. chmod a=rx test

C. chmod u=rx,a-rx test

D. chmod u+w,g+rx,o+rx test

 

Answer: B

 

How do you activate an ACL when mounting a file system manually?

A. mount –acl /dev/hda5 /data

B. mount -f acl /dev/hda5 /data

C. mount -o acl /dev/hda5 /data

D. mount –use-acl /dev/hda5 /data

 

Answer: C

 

you have a test directory with the following permissions: rwx—— You want to change the

permissions to the following values: r-xr-xr-x. Which command accomplishes this?

 

A. chmod 777 test

B. chmod u=rx,a-rx test

C. chmod u-w,g+rx,o+rx test

D. chmod u+w,g+rx,o+rx test

 

Answer: C

 

What does the following line of the sudo configuration file mean? geeko ALL = /sbin/shutdown

 

A. All users are allowed to shut down the computer.

B. It allows the user geeko to shut down the computer.

C. All users (except geeko) are allowed to shut down the computer.

D. User geeko is allowed to shut down the computer with name ALL.

E. All users of the computer with the name geeko are allowed to shut down the computer.

 

Answer: B

 

What is the key characteristic of the root account?

 

A. The user name root

B. The User ID (UID) 0

C. The Security Identifier (SID)

D. The Universally Unique Identifier (UUID)

 

Answer: B

 

Which statement about an incremental backup is correct?

A. The use of incremental backups is limited to backups on tapes.

B. To restore an incremental backup, you need the last incremental backup only.

C. To restore an incremental backup, you need the last full backup and the last incremental

backup that was made since the last full backup.

D. The amount of data that needs to be backed up with each incremental backup depends only on

the amount of data changed the last incremental backup.

 

Answer: D

 

Which options are PAM module types that can be used in a PAM configuration file? (Choose 4.)

A. key

B. auth

C. card

D. account

E. session

F. password

 

Answer: B,D,E,F

 

Which command shows you the default shell of a user?

 

A. w user

B. id user

C. who user

D. finger user

sts.com

Answer: D

 

Suppose you change from your current runlevel 5 to the new runlevel 3. Which statement is correct?

A. Nothing will happen at all.

B. If there is a K* link for a certain service in /etc/init.d/rc5.d/ but no corresponding S* link I/etc/init.d/rc3.d/, nothing will happen.

C. If there is no K* link for a certain service in /etc/init.d/rc5.d/ but there is an S* link in

/etc/init.d/rc3.d/, the service is started.

D. If there is a K* link for a certain service in /etc/init.d/rc5.d/ and there is an S* link in

/etc/init.d/rc3.d/, the service is stopped and started again.

 

Answer: C

 

In a terminal window, which command can you enter to change to your home directory

(/home/geeko)? (Choose 2.)

 

A. cd

B. cd ~

C. cd -h

D. cd home

E. cd –homedir

 

Answer: A,B

 

You have a file named file1 and you want to create a symbolic link named link-to-file1 to the file. In

a terminal window, which command accomplishes what you want? (Choose 2.)

A. ln file link-to-file1

B. ln link-to-file1 file1

C. ln -s file1 link-to-file1

D. ln -s link-to-file1 file1

E. cp -s file1 link-to-file1

F. mv -s file1 link-to-file1

 

Answer: C,E

 

Which are configuration files of syslog-ng? (Choose 3.)

A. /etc/logging

B. /etc/sysconfig/log

C. /etc/log/syslog-ng

D. /etc/sysconfig/syslog

E. /etc/log/syslog-ng.conf

F. /etc/syslog-ng/syslog-ng.conf

G. /etc/syslog-ng/syslog-ng.conf.in

 

Answer: D,F,G

 

The useradd command is used to create new users. Which file contains information on the primary group, shell, and other parameters to be used by useradd when not specified on the command line?

 

A. /etc/profile

B. /etc/passwd

C. /etc/shadow

D. /etc/default/useradd

 

Answer: D

 

What does the following command do? tar -tzvf /tmp/backup.tgz etc/HOSTNAME

A. It extracts the etc/HOSTNAME file from the /tmp/backup.tgz archive.

B. It includes the etc/HOSTNAME file in the /tmp/backup.tgz archive.

C. It produces an error message because the options are in the wrong sequence.

D. It displays a line similar to the following, but otherwise does nothing: -rw-r–r– root/root 23 2005-

03-11 14:20 etc/HOSTNAME

 

Answer: D

 

As root, you entered the runlevel command. What does the following output indicate? N5

 

A. You are in runlevel 5. A previous runlevel is not available.

B. You are in runlevel 5. A previous runlevel was 3 (network).

C. You are in runlevel 3 (network). The system is changing now to runlevel 5.

D. You are currently in no runlevel. The system is changing now to runlevel 5.

 

Answer: A

 

You need to find the files in the /etc directory that contain the word DocumentRoot. In a terminal

window, which command will help you find it?

 

A. discover DocumentRoot /etc

B. grep -r DocumentRoot /etc/*

C. search -r DocumentRoot /etc/*

D. find /etc -content DocumentRoot

 

Answer: B

 

You can schedule jobs to be executed by cron in several ways. Which directories are used for scripts that are to be executed at regular intervals? (Choose 2.)

 

A. /etc/cron.d/

B. /etc/crontabs/

C. /etc/cron.daily/

D. /var/spool/cron/tabs/

 

Answer: A,C

 

As a normal user, such as geeko, you use the lpoptions command to change printer options, such as the page size. To which file are these options saved?

 

A. ~/.bashrc

B. ~/.lpoptions

C. /etc/cups/lpoptions

D. /etc/sysconfig/cups

 

Answer: B

 

Which command displays cpu and input/output statistics for devices and partitions?

 

A. siga

B. sitar

C. fdisk

D. lspci

E. iostat

F. hwinfo

G. hdparm

 

Answer: E

What is the result of the following command? (Choose 2.)

 

dd if=/dev/zero of=/dev/hdd bs=512 count=1

A. Overwrites an existing partition table

B. Creates a LVM partition of 512 blocks

C. Backs up the /dev/zero and /dev/hdd files

D. Writes zeros in the first 512 bytes of the first hard disk block

E. Assigns the physical volume zero to the logical volume hdd

 

Answer: A,D

You do not want to see any error messages when using the find command; you want to see onl

the results. Which command accomplishes this task?

A. find /etc -name “*conf” 0>/dev/null

B. find /etc -name “*conf” 1>/dev/null

C. find /etc -name “*conf” 2>/dev/null

D. find /etc -name “*conf” 3>/dev/null

 

Answer: C

 

In a terminal window, your current working directory is /home/geeko. You want to change to the /tmp directory. Which command will make the desired change of directories? (Choose 2.)

 

A. cd tmp

B. cd /tmp

C. cd ./tmp

D. cwd /tmp

E. cd ../tmp

F. cd ../../tmp

 

Answer: B,F

 

Why are the noauto and users options used with /etc/fstab?

A. A normal user is not allowed to access this partition.

B. They allow any user to mount and unmount a partition.

C. They specify the partitions that are bootable by a user.

D. They specify the partitions that are not bootable by a user.

 

Answer: B

 

You have a /tmp/data directory containing the files .file, file1, and file2. You want to copy the file1 and file2 files only to the /data-old directory that already exists. In a terminal window, which command acomplishes this?

 

A. cp /tmp/data /data-old

B. cp /tmp/data/. /data-old

C. cp /tmp/data/* /data-old

D. cp /tmp/data/? /data-old

 

Answer: C

 

You entered the following as a boot option in the GRUB boot screen: nit=/bin/bash What does the option mean?

A. The bash is used as the default shell.

B. Linux starts without a graphical environment.

C. The system is started directly in a bash shell. You are automatically logged in as root without

being asked for a password.

D. The system is started directly in a bash shell. You are automatically logged in as default user

without being asked for a password.

E. The system is started directly in a bash shell. You are automatically asked for the root

password before you are logged in as root.

F. The system is started directly in a bash shell. You are automatically asked for the default user’s

password before you are logged in.

 

Answer: C

 

You want to view the last 20 lines of the /var/log/messages file and any new lines that are

subsequently added by syslog to this file. Which command would you use?

 

A. tail -20f /var/log/messages

B. end -20f /var/log/messages

C. less -20f /var/log/messages

D. follow -20 /var/log/messages

 

Answer: A

 

Which RAID level is described by the following sentence? This level improves the performance of your data access; however, it does not provide redundancy.

 

A. RAID 0

B. RAID 1

C. RAID 4

D. RAID 5

E. RAID 6

 

Answer: A

 

 

To which process does the process ID 1 always belong?

A. init

B. boot

C. cron

D. X server

E. kernel (vmlinuz)

 

Answer: A

 

Which command would you use to start the xeyes program in the background?

A. xeyes &

B. xeyes &&

C. bg | xeyes

D. xeyes -bg

E. xeyes | bg

F. xeyes > bg

 

Answer: A

 

Which command creates the .depend.boot, .depend.start, and .depend.stop files in /etc/init.d/?

 

A. init

B. insserv

C. mkinitrd

D. mkreiserfs

 

Answer: B

 

Which command can you use to check an ext2/ext3 file system for a correct superblock, faulty

data blocks, or faulty allocation of data blocks?

 

A. df

B. du

C. fdisk

D. e2fsck

E. reiserfsck

 

Answer: D

 

Which statements about the LVM components are correct? (Choose 2.)

 

A. A volume group is part of a logical volume.

B. Logical volumes are grouped in a master group.

C. A volume group always consists of one physical volume.

D. A physical volume can be a partition or an entire hard disk.

E. A volume group can be reduced in size by removing physical volumes.

F. The operating system accesses the volume groups like conventional physical partitions.

 

Answer: D,E

 

When SUSE Linux Enterprise Server 10 starts, some boot messages scroll by on the screen

quickly. What is the name of the file in /var/log/ where these messages are stored?

 

Answer: /var/log/boot.msg


Screenshot_1

Screenshot_4


Screenshot_6 Screenshot_7 Screenshot_8 Screenshot_9 Screenshot_10 Screenshot_11 Screenshot_12 Screenshot_13 Screenshot_14 Screenshot_15 Screenshot_16 Screenshot_17 Screenshot_18 Screenshot_19 Screenshot_20 Screenshot_21 Screenshot_22 Screenshot_23 Screenshot_24 Screenshot_25 Screenshot_26Screenshot_54