Difficult Red Hat Certification Exam Interview Preparation Guide Download PDF
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40 Red Hat Certification Questions and Answers:
Table of Contents:
1 :: Explain Both RAID level 0 and Linear RAID provide capacity equivalent to the amount of storage you have. In other
words, there is no space reserved for parity or error checking. What, then, is the difference between RAID
level 0 and Linear RAID?
A. When using Linear RAID, data is not striped across drives.
B. When using Linear RAID, data is striped across drives.
C. RAID 0 provides some amount of error checking.
D. Linear RAID provides some amount of redundancy.
A. When using Linear RAID, data is not striped across drives.
3 :: Explain What DHCP server option is used to specify the DNS server to clients?
A. domain-name-servers
B. dns
C. domain-name
D. routers
A. domain-name-servers
4 :: Do you know One Logical Volume is created named as myvol under vo volume group and is
mounted. The Initial Size of that Logical Volume is 124MB. Make successfully that
the size of Logical Volume 245MB without losing any data. The size of logical
volume 240MB to 255MB will be acceptable.
1. First check the size of Logical Volume: lvdisplay /dev/vo/myvol
2. Increase the Size of Logical Volume: lvextend -L+121M /dev/vo/myvol
3. Make Available the size on online: resize2fs /dev/vo/myvol
4. Verify the Size of Logical Volume: lvdisplay /dev/vo/myvol
5. Verify that the size comes in online or not: df -h
We can extend the size of logical Volume using the lvextend command. As well as to
decrease the size of Logical Volume, use the lvresize command. In LVM v2 we can
extend the size of Logical Volume without unmount as well as we can bring the actual
size of Logical Volume on online using ext2online command.
2. Increase the Size of Logical Volume: lvextend -L+121M /dev/vo/myvol
3. Make Available the size on online: resize2fs /dev/vo/myvol
4. Verify the Size of Logical Volume: lvdisplay /dev/vo/myvol
5. Verify that the size comes in online or not: df -h
We can extend the size of logical Volume using the lvextend command. As well as to
decrease the size of Logical Volume, use the lvresize command. In LVM v2 we can
extend the size of Logical Volume without unmount as well as we can bring the actual
size of Logical Volume on online using ext2online command.
6 :: Suppose You are a System administrator. Using Log files very easy to monitor the system.
Now there are 50 servers running as Mail, Web, Proxy, DNS services etc. You want
to centralize the logs from all servers into on LOG Server. How will you configure
the LOG Server to accept logs from remote host?
By Default system accept the logs only generated from local host. To accept the Logfrom other host configure:
1. vi /etc/sysconfig/syslog
SYSLOGD_OPTIONS="-m 0 -r"
Where
-m 0 disables 'MARK' messages.
-r enables logging from remote machines
-x disables DNS lookups on messages recieved with -r
2. service syslog restart
1. vi /etc/sysconfig/syslog
SYSLOGD_OPTIONS="-m 0 -r"
Where
-m 0 disables 'MARK' messages.
-r enables logging from remote machines
-x disables DNS lookups on messages recieved with -r
2. service syslog restart
7 :: Explain One Package named zsh is dump on ftp://server1.example.com under /pub/updates
directory and your FTP server is 192.168.0.254. Install the package zsh.
1. rpm -ivh ftp://server1/example.com/pub/updates/zsh-*
or
1. Login to ftp server : ftp ftp://server1.example.com using anonymous user.
2. Change the directory: cd pub and cd updates
3. Download the package: mget zsh-*
4. Quit from the ftp prompt : bye
5. Install the package
6. rpm -ivh zsh-*
7. Verify either package is installed or not : rpm -q zsh
or
1. Login to ftp server : ftp ftp://server1.example.com using anonymous user.
2. Change the directory: cd pub and cd updates
3. Download the package: mget zsh-*
4. Quit from the ftp prompt : bye
5. Install the package
6. rpm -ivh zsh-*
7. Verify either package is installed or not : rpm -q zsh
8 :: Do you know Quota is implemented on /data but not working properly. Find out the
Problem and implement the quota to user1 to have a soft limit 60 inodes
(files) and hard limit of 70 inodes (files).
Quotas are used to limit a user's or a group of users' ability to consume disk space. This
prevents a small group of users from monopolizing disk capacity and potentially
interfering with other users or the entire system. Disk quotas are commonly used by ISPs,
by Web hosting companies, on FTP sites, and on corporate file servers to ensure
continued availability of their systems.
Without quotas, one or more users can upload files on an FTP server to the point of
filling a filesystem. Once the affected partition is full, other users are effectively denied
upload access to the disk. This is also a reason to mount different filesystem directories
on different partitions. For example, if you only had partitions for your root (/) directory
and swap space, someone uploading to your computer could fill up all of the space in
your root directory (/). Without at least a little free space in the root directory (/), your
system could become unstable or even crash.
You have two ways to set quotas for users. You can limit users by inodes or by kilobytesized
disk blocks. Every Linux file requires an inode. Therefore, you can limit users by
the number of files or by absolute space. You can set up different quotas for different
filesystems. For example, you can set different quotas for users on the /home and /tmp
directories if they are mounted on their own partitions.
Limits on disk blocks restrict the amount of disk space available to a user on your system.
Older versions of Red Hat Linux included LinuxConf, which included a graphical tool to
configure quotas. As of this writing, Red Hat no longer has a graphical quota
configuration tool. Today, you can configure quotas on RHEL only through the command
line interface.
1. vi /etc/fstab
/dev/hda11 /data ext3 defaults,usrquota 1 2
2. Either Reboot the System or remount the partition.
Mount -o remount /dev/hda11 /data
3. touch /data/aquota.user
4. quotacheck -ufm /data
5. quotaon -u /data
6. edquota -u user1 /data
and Specified the Soft limit and hard limit on opened file.
prevents a small group of users from monopolizing disk capacity and potentially
interfering with other users or the entire system. Disk quotas are commonly used by ISPs,
by Web hosting companies, on FTP sites, and on corporate file servers to ensure
continued availability of their systems.
Without quotas, one or more users can upload files on an FTP server to the point of
filling a filesystem. Once the affected partition is full, other users are effectively denied
upload access to the disk. This is also a reason to mount different filesystem directories
on different partitions. For example, if you only had partitions for your root (/) directory
and swap space, someone uploading to your computer could fill up all of the space in
your root directory (/). Without at least a little free space in the root directory (/), your
system could become unstable or even crash.
You have two ways to set quotas for users. You can limit users by inodes or by kilobytesized
disk blocks. Every Linux file requires an inode. Therefore, you can limit users by
the number of files or by absolute space. You can set up different quotas for different
filesystems. For example, you can set different quotas for users on the /home and /tmp
directories if they are mounted on their own partitions.
Limits on disk blocks restrict the amount of disk space available to a user on your system.
Older versions of Red Hat Linux included LinuxConf, which included a graphical tool to
configure quotas. As of this writing, Red Hat no longer has a graphical quota
configuration tool. Today, you can configure quotas on RHEL only through the command
line interface.
1. vi /etc/fstab
/dev/hda11 /data ext3 defaults,usrquota 1 2
2. Either Reboot the System or remount the partition.
Mount -o remount /dev/hda11 /data
3. touch /data/aquota.user
4. quotacheck -ufm /data
5. quotaon -u /data
6. edquota -u user1 /data
and Specified the Soft limit and hard limit on opened file.
9 :: Tell me The System you are using is for NFS (Network File Services). Some important data
are shared from your system. Make automatically start the nfs and portmap
services at boot time.
We can control the services for current session and for next boot time also. For current
Session, we use service servicename start or restart or stop or status. For automatically on
next reboot time:
1. chkconfig servicename on or off
eg: chkconfig nfs on
chkconfig portmap on
or
ntsysv
Select the nfs and portmap services.
2. Reboot the system and identify whether services are running or not.
Session, we use service servicename start or restart or stop or status. For automatically on
next reboot time:
1. chkconfig servicename on or off
eg: chkconfig nfs on
chkconfig portmap on
or
ntsysv
Select the nfs and portmap services.
2. Reboot the system and identify whether services are running or not.
10 :: Suppose One Logical Volume named lv1 is created under vg0. The Initial Size of that Logical
Volume is 100MB. Now you required the size 500MB. Make successfully the size of
that Logical Volume 500M without losing any data. As well as size should be
increased online.
The LVM system organizes hard disks into Logical Volume (LV) groups. Essentially,
physical hard disk partitions (or possibly RAID arrays) are set up in a bunch of equalsized chunks known as
Physical Extents (PE). As there are several other concepts
associated with the LVM system, let's start with some basic definitions:
Physical Volume (PV) is the standard partition that you add to the LVM mix.
Normally, a physical volume is a standard primary or logical partition. It can also
be a RAID array.
Physical Extent (PE) is a chunk of disk space. Every PV is divided into a number
of equal sized PEs. Every PE in a LV group is the same size. Different LV groups
can have different sized PEs.
Logical Extent (LE) is also a chunk of disk space. Every LE is mapped to a
specific PE.
Logical Volume (LV) is composed of a group of LEs. You can mount a
filesystem such as /home and /var on an LV.
Volume Group (VG) is composed of a group of LVs. It is the organizational
group for LVM. Most of the commands that you'll use apply to a specific VG.
1. Verify the size of Logical Volume: lvdisplay /dev/vg0/lv1
2. Verify the Size on mounted directory: df -h or df -h mounted directory name
3. Use : lvextend -L+400M /dev/vg0/lv1
4. resize2fs /dev/vg0/lv1 to bring extended size online.
5. Again Verify using lvdisplay and df -h command.
physical hard disk partitions (or possibly RAID arrays) are set up in a bunch of equalsized chunks known as
Physical Extents (PE). As there are several other concepts
associated with the LVM system, let's start with some basic definitions:
Physical Volume (PV) is the standard partition that you add to the LVM mix.
Normally, a physical volume is a standard primary or logical partition. It can also
be a RAID array.
Physical Extent (PE) is a chunk of disk space. Every PV is divided into a number
of equal sized PEs. Every PE in a LV group is the same size. Different LV groups
can have different sized PEs.
Logical Extent (LE) is also a chunk of disk space. Every LE is mapped to a
specific PE.
Logical Volume (LV) is composed of a group of LEs. You can mount a
filesystem such as /home and /var on an LV.
Volume Group (VG) is composed of a group of LVs. It is the organizational
group for LVM. Most of the commands that you'll use apply to a specific VG.
1. Verify the size of Logical Volume: lvdisplay /dev/vg0/lv1
2. Verify the Size on mounted directory: df -h or df -h mounted directory name
3. Use : lvextend -L+400M /dev/vg0/lv1
4. resize2fs /dev/vg0/lv1 to bring extended size online.
5. Again Verify using lvdisplay and df -h command.
12 :: Suppose You are new System Administrator and from now you are going to handle the system and your
main task is Network monitoring, Backup and Restore. But you dont know the root password.
Change the root password to redhat and login in default Runlevel.
When you Boot the System, it starts on default Runlevel specified in /etc/inittab:
Id::initdefault:
When System Successfully boot, it will ask for username and password. But you dont know the
roots password.
1. Restart the System.
2. You will get the boot loader GRUB screen.
3. Press a and type 1 or s for single mode
ro root=LABEL=/ rhgb queit 1
4. System will boot on Single User mode.
5. Use passwd command to change.
6. Set redhat password.
7. Press ctrl+d
Id::initdefault:
When System Successfully boot, it will ask for username and password. But you dont know the
roots password.
1. Restart the System.
2. You will get the boot loader GRUB screen.
3. Press a and type 1 or s for single mode
ro root=LABEL=/ rhgb queit 1
4. System will boot on Single User mode.
5. Use passwd command to change.
6. Set redhat password.
7. Press ctrl+d
14 :: Suppose You are giving RHCT Exam and in your Exam paper there is a question written, make
successfully ping to 192.168.0.254.
Network problem think to check:
1. IP Configuration: use ifconfig command either IP is assigned to interface or not?
2. Default Gateway is set or not?
3. Hostname is set or not?
4. Routing problem is there?
5. Device Driver Module is loaded or not?
6. Device is activated or not?
Check In this way:
1. use ifconfig command and identify which IP is assigned or not.
2. cat /etc/sysconfig/network What, What is written here. Actually here are these parameters.
NETWORKING=yes or no
GATEWAY=x.x.x.x
HOSTNAME=?
NISDOMAIN=?
- Correct the file
3. Use netconfig command
- Either Select Automatically from DHCP or assign the static IP
4. Use service network restart or start command
Now try to ping it will work.
1. IP Configuration: use ifconfig command either IP is assigned to interface or not?
2. Default Gateway is set or not?
3. Hostname is set or not?
4. Routing problem is there?
5. Device Driver Module is loaded or not?
6. Device is activated or not?
Check In this way:
1. use ifconfig command and identify which IP is assigned or not.
2. cat /etc/sysconfig/network What, What is written here. Actually here are these parameters.
NETWORKING=yes or no
GATEWAY=x.x.x.x
HOSTNAME=?
NISDOMAIN=?
- Correct the file
3. Use netconfig command
- Either Select Automatically from DHCP or assign the static IP
4. Use service network restart or start command
Now try to ping it will work.
15 :: Explain Which of the following is a journaling filesystem?
A. ext2
B. vfat
C. minix
D. ext3
D. ext3
16 :: Suppose You are new System Administrator and from now you are going to handle the
system and your main task is Network monitoring, Backup and Restore. But you
dont know the root password. Change the root password to redhat and login in
default Runlevel.
When you Boot the System, it starts on default Runlevel specified in /etc/inittab:
Id:?:initdefault:
When System Successfully boot, it will ask for username and password. But you don't
know the root's password. To change the root password you need to boot the system into
single user mode. You can pass the kernel arguments from the boot loader.
1. Restart the System.
2. You will get the boot loader GRUB screen.
3. Press a and type 1 or s for single mode
ro root=LABEL=/ rhgb queit s
4. System will boot on Single User mode.
5. Use passwd command to change.
6. Press ctrl+d
Id:?:initdefault:
When System Successfully boot, it will ask for username and password. But you don't
know the root's password. To change the root password you need to boot the system into
single user mode. You can pass the kernel arguments from the boot loader.
1. Restart the System.
2. You will get the boot loader GRUB screen.
3. Press a and type 1 or s for single mode
ro root=LABEL=/ rhgb queit s
4. System will boot on Single User mode.
5. Use passwd command to change.
6. Press ctrl+d
17 :: How to Add a new logical partition having size 100MB and create the /data which will be
the mount point for the new partition.
1. Use fdisk /dev/hda ->To create new partition.
2. Type n-> For New partitions
3. It will ask for Logical or Primary Partitions. Press l for logical.
4. It will ask for the Starting Cylinder: Use the Default by pressing Enter Key.
5. Type the Size: +100M ->You can Specify either Last cylinder of Size here.
6. Press P to verify the partitions lists and remember the partitions name.
7. Press w to write on partitions table.
8. Either Reboot or use partprobe command.
9. Use mkfs -t ext3 /dev/hda?
10. Or
11. mke2fs -j /dev/hda? To create ext3 filesystem.
12. vi /etc/fstab
13. Write:
14. /dev/hda? /data ext3 defaults 0 0
11. Verify by mounting on current Sessions also:
15. mount /dev/hda? /data
2. Type n-> For New partitions
3. It will ask for Logical or Primary Partitions. Press l for logical.
4. It will ask for the Starting Cylinder: Use the Default by pressing Enter Key.
5. Type the Size: +100M ->You can Specify either Last cylinder of Size here.
6. Press P to verify the partitions lists and remember the partitions name.
7. Press w to write on partitions table.
8. Either Reboot or use partprobe command.
9. Use mkfs -t ext3 /dev/hda?
10. Or
11. mke2fs -j /dev/hda? To create ext3 filesystem.
12. vi /etc/fstab
13. Write:
14. /dev/hda? /data ext3 defaults 0 0
11. Verify by mounting on current Sessions also:
15. mount /dev/hda? /data
18 :: Suppose There are more then 400 Computers in your Office. You are appointed as a System
Administrator. But you don?t have Router. So, you are going to use your One Linux Server as a
Router. How will you enable IP packets forward?
1. /proc is the virtual filesystem, we use /proc to modify the kernel value at running time. So For
Current Session: echo ?1? >/proc/sys/net/ipv4/ip_forward
2. /etc/sysctl.conf ?when System Reboot on next time, /etc/rc.d/rc.sysinit scripts reads the file
/etc/sysctl.conf. So if you want to permanently set the IP forwarding enable, You should set:
net.ipv4.ip_forward=1
Here 0 means disable, 1 means enable.
Current Session: echo ?1? >/proc/sys/net/ipv4/ip_forward
2. /etc/sysctl.conf ?when System Reboot on next time, /etc/rc.d/rc.sysinit scripts reads the file
/etc/sysctl.conf. So if you want to permanently set the IP forwarding enable, You should set:
net.ipv4.ip_forward=1
Here 0 means disable, 1 means enable.
19 :: Suppose You are giving the debug RHCT exam. The examiner told you that the password of root is redhat.
When you tried to login displays the error message and redisplayed the login screen. You
changed the root password, again unable to login as a root.
How will you make Successfully Login as a root.
When root unable to login into the system think:
1. Is password correct?
2. Is account expired?
3. Is terminal Blocked?
Do these Steps:
1. Boot the System on Single user mode.
2. Change the password
3. Check the account expire date by using chage ?l root command.
If account is expired, set net expire date: chage ?E ?NEVER? root
4. Check the file /etc/securetty ?Which file blocked to root login from certain terminal.
5. If terminal is deleted or commented write new or uncomment.
6. Reboot the system and login as a root.
1. Is password correct?
2. Is account expired?
3. Is terminal Blocked?
Do these Steps:
1. Boot the System on Single user mode.
2. Change the password
3. Check the account expire date by using chage ?l root command.
If account is expired, set net expire date: chage ?E ?NEVER? root
4. Check the file /etc/securetty ?Which file blocked to root login from certain terminal.
5. If terminal is deleted or commented write new or uncomment.
6. Reboot the system and login as a root.
20 :: How to Make a swap partition having 100MB. Make Automatically Usable at System Boot Time.
1. Use fdisk /dev/hda ?To create new partition.
2. Type n ?For New partition
3. It will ask for Logical or Primary Partitions. Press l for logical.
4. It will ask for the Starting Cylinder: Use the Default by pressing Enter Key.
5. Type the Size: +100M ?You can Specify either Last cylinder of Size here.
6. Press P to verify the partitions lists and remember the partitions name.
Default System ID is 83 that means Linux Native.
7. Type t to change the System ID of partition.
8. Type Partition Number
9. Type 82 that means Linux Swap.
10. Press w to write on partitions table.
11. Either Reboot or use partprobe command.
12. mkswap /dev/hda? ?To create Swap File system on partition.
13. swapon /dev/hda? ?To enable the Swap space from partition.
14. free ?m ?Verify Either Swap is enabled or not.
15. vi /etc/fstab
/dev/hda? swap swap defaults 0 0
16. Reboot the System and verify that swap is automatically enabled or not.
2. Type n ?For New partition
3. It will ask for Logical or Primary Partitions. Press l for logical.
4. It will ask for the Starting Cylinder: Use the Default by pressing Enter Key.
5. Type the Size: +100M ?You can Specify either Last cylinder of Size here.
6. Press P to verify the partitions lists and remember the partitions name.
Default System ID is 83 that means Linux Native.
7. Type t to change the System ID of partition.
8. Type Partition Number
9. Type 82 that means Linux Swap.
10. Press w to write on partitions table.
11. Either Reboot or use partprobe command.
12. mkswap /dev/hda? ?To create Swap File system on partition.
13. swapon /dev/hda? ?To enable the Swap space from partition.
14. free ?m ?Verify Either Swap is enabled or not.
15. vi /etc/fstab
/dev/hda? swap swap defaults 0 0
16. Reboot the System and verify that swap is automatically enabled or not.
22 :: Suppose In order to open up an SSH shell on a remote machine called tiger using the login name of admin,
what would be the proper command line for this?
A. openssh -l admin tiger
B. ssh -l admin tiger
C. ssh admin@tiger
D. sshd tiger admin
B. ssh -l admin tiger
C. ssh admin@tiger
C. ssh admin@tiger
23 :: What is the main configuration file for XFree86 version 4?
A. /etc/X11/XF86Config
B. /etc/X11/XF86Config-4
C. /usr/X11R6/bin/XFree86
D. XF86_SVGA
B. /etc/X11/XF86Config-4
24 :: Suppose You Completely Install the Redhat Enterprise Linux 5 on your System. While start
the system, its giving error to load X window System. How will you fix that
problem and make boot successfully run X Window System.
Think while Problems occurred on booting System on Runlevel 5 (X Window).
1. /tmp is full or not
2. Quota is already reached
3. Video card or resolution or monitor is misconfigured.
4. xfs service is running or not.
Do These:
1. df -h /tmp /tmp is full remove the unnecessary file
2. quota username if quota is already reached remove unnecessary file from home
directory.
3. Boot the System in runlevel 3. you can pass the Kernel Argument from boot
loader.
4. Use command: system-config-display It will display a dialog to configure the
monitor, Video card, resolution etc.
5. Set the Default Runlevel 5 in /etc/inittab
id:5:initdefault:
6. Reboot the System you will get the GUI login Screen.
1. /tmp is full or not
2. Quota is already reached
3. Video card or resolution or monitor is misconfigured.
4. xfs service is running or not.
Do These:
1. df -h /tmp /tmp is full remove the unnecessary file
2. quota username if quota is already reached remove unnecessary file from home
directory.
3. Boot the System in runlevel 3. you can pass the Kernel Argument from boot
loader.
4. Use command: system-config-display It will display a dialog to configure the
monitor, Video card, resolution etc.
5. Set the Default Runlevel 5 in /etc/inittab
id:5:initdefault:
6. Reboot the System you will get the GUI login Screen.
25 :: Suppose There are two different networks, 192.168.0.0/24 and 192.168.1.0/24. Your System is
in 192.168.0.0/24 Network. One RHEL 5 Installed System is going to use as a
Router. All required configuration is already done on Linux Server. Where
192.168.0.254 and 192.168.1.254 IP Address are assigned on that Server. How will
make successfully ping to 192.168.1.0/24 Networks Host?
1. vi /etc/sysconfig/network
GATEWAY=192.168.0.254
OR
vi /etc/sysconf/network-scripts/ifcfg-eth0
DEVICE=eth0
BOOTPROTO=static
ONBOOT=yes
IPADDR=192.168.0.?
NETMASK=255.255.255.0
GATEWAY=192.168.0.254
2. service network restart
vim /etc/sysctel
where is 0 set 1 in first line
save file
systecl -p
GATEWAY=192.168.0.254
OR
vi /etc/sysconf/network-scripts/ifcfg-eth0
DEVICE=eth0
BOOTPROTO=static
ONBOOT=yes
IPADDR=192.168.0.?
NETMASK=255.255.255.0
GATEWAY=192.168.0.254
2. service network restart
vim /etc/sysctel
where is 0 set 1 in first line
save file
systecl -p
