Advanced Level Linux Certification


What is the minimum number of disks required in a RAID5 array?

A. 1

B. 2

C. 3

D. 4

E. 5

Answer: C



RAID 5: Block-level striping with distributed parity. Minimum 3 disks.


A server has three disks of 80GB each and must manage a database with 4 million records of 30KB each. The best configuration for this server, with the criteria being performance, configurability and flexibility, is:

A. Use just LVM

B. Use RAID1 over LVM

C. Use LVM over RAID5

D. Use LVM over RAID1

E. Use RAID5 over LVM

Answer: C


RAID1 would not be performance enhancing (Mirroring), as would the default LVM (linear). So use a RAID5 for redundancy and performance and use LVM for added configurability and flexibility

A striped LVM only would work too, I guess, if you need no redundancy at all.


The correct command sequence to create logical volumes on a Linux system is:

A. lvcreate, pvcreate, vgcreate, mount, mke2fs

B. pvcreate, vgcreate, lvcreate, mke2fs, mount

C. vgcreate, lvcreate, pvcreate, mount, mke2fs

D. mke2fs, pvcreate, vgcreate, lvcreate, mount

E. pvcreate, lvcreate, vgcreate, mount, mke2fs

Answer: B



You need to create the Physical Volumes first, then the Volume Group (consisting of PVs), then the Logical Volumes, which you need to format and mount.


What is the usable disk space of a RAID 5 array of five 18GB drives with one drive dedicated as a spare?

A. 18GB

B. 36GB

C. 54GB

D. 72GB

E. 90GB

Answer: C



RAID5 capacity is available disks - 1. 5 disks - 1 - 1 spare = 3 disks. 3 x 18 = 54


You decide to use the logical volume manager (LVM) to manage four 4GB disk drives. After creating the volume group, how would you create a 10GB logical volume called big-app?

A. vgcreate -p 10g -n /dev/vg01/big-app

B. vgcreate -l 2560 /dev/vg01/big-app

C. mklvm -v 10240 -n /dev/vg01/big-app

D. lvcreate -v 10240 /dev/vg01/big-app

E. lvcreate -l 2560 vg01 -n big-app

Answer: E


From the man pages:

lvcreate - create a logical volume in an existing volume group

-l, --extents LogicalExtentsNumber[%{VG|PVS|FREE}]

Gives the number of logical extents to allocate for the new logical volume. This can also be expressed as a percentage of the total space in the Volume Group with the suffix %VG, of the remaining free space in the Volume Group with the suffix %FREE, or of the remaining free space for the specified PhysicalVolume(s) with the suffix %PVS

-n, --name LogicalVolumeName The name for the new logical volume. Without this option a default names of "lvol#" will be generated where # is the LVM internal number of the logical volume.


What is the purpose of vgextend?

A. Extend a volume group's footprint on disk

B. Add physical volumes to a volume group

C. Increase the number of days between scheduled error checking

D. Create a volume group which uses all available space on disk

Answer: B


From the man pages:

vgextend - add physical volumes to a volume group


Which RAID level provides the most redundancy?





Answer: C



a,b) only 1 disk may fail, regardless how many disks are in the RAID

d) no disk may fail

c) n - 1 disks may fail


Which pseudo-file contains information on the status of software RAID devices?

A. /proc/raidstat

B. /proc/mdstatus

C. /proc/raidstatus

D. /proc/mdstat

E. /proc/raid/status

Answer: D


From the man pages:

/proc/mdstat If you're using the /proc filesystem, /proc/mdstat lists all active md devices with information about them. mdadm uses this to find arrays when --scan is given in Misc mode, and to monitor array reconstruction on Monitor mode.


What information does the file modules.dep provide?

A. A list of all modules available to the kernel.

B. A list of modules required by each module.

C. A list of devices and their module name.

D. A list of modules compiled for this kernel.

E. A list of modules the kernel needs to run.

Answer: B


From the man pages:

The modules.dep.bin as generated by module-init-tools depmod, lists the dependencies for every module in the directories under /lib/modules/version, where modules.dep.bin (or the human readable version modules.

dep) is also located. It is used by utilities such as modprobe. The binary version will be used by default, if it was generated by a compatible version of depmod, with fallback to the generic modules.dep.

These files are not intended for editing or use by any additional utilities as their format is subject to change in the future. You should use the modinfo(8) command to obtain information about modules in a future proof and compatible fashion rather than touching these files.


Before compiling a new kernel, what needs to be done?

A. Compile kernel modules

B. Configure the kernel options

C. Delete old kernel sources

D. Change to runlevel 1

E. All of the above

Answer: B




On a system with separate partitions for /, /usr, /var, /tmp, which filesystem[s] can safely be mounted readonly?

A. /var, /usr

B. /var

C. /usr, /, /tmp

D. /usr

E. /tmp

Answer: D


/tmp and /var both need to be written to. /usr is the most static of the directories (excluding /usr/local)


Which of the following best describes the format of the /etc/fstab file?

A. mount point; device name; filesystem type; mount options; dump filesystem; fsck order

B. device name; mount point; filesystem type; mount options; dump filesystem; fsck order

C. mount point; filesystem type; device name; mount options; dump filesystem; fsck order

D. device name; mount point; mount options; filesystem type; dump filessystem; fsck order

E. device name; filesystem type; mount point; mount options; dump filesystem; fsck order

Answer: B


From the man pages:

The first field, (fs_spec), describes the block special device or remote filesystem to be mounted.

The second field, (fs_file), describes the mount point for the filesystem. For swap partitions, this field should be specified as `none'.

The third field, (fs_vfstype), describes the type of the filesystem.

The fourth field, (fs_mntops), describes the mount options associated with the filesystem.

The fifth field, (fs_freq), is used for these filesystems by the dump(8) command to determine which filesystems need to be dumped.

The sixth field, (fs_passno), is used by the fsck(8) program to determine the order in which filesystem checks are done at reboot time.


Which of the following is a valid location in the automount configuration, when a Windows share needs to be made available to the system?

A. \\server\sharename

B. ://server/sharename

C. server:/sharename

D. :server/sharename

E. \\\\server\\sharename

Answer: B


From the man pages:


kernel -ro,soft,intr

boot -fstype=ext2 :/dev/hda1

windoze -fstype=smbfs ://windoze/c

removable -fstype=ext2 :/dev/hdd

cd -fstype=iso9660,ro :/dev/hdc

floppy -fstype=auto :/dev/fd0

server -rw,hard,intr / -ro \

/usr \


In the first line we have a NFS remote mount of the kernel directory on This is mounted readonly.

The second line mounts an ext2 volume on a local ide drive. The third makes a share exported from a

Windows machine available for automounting. The rest should be fairly self-explanatory. The last entry (the last three lines) is an example of a multi-map (see below).


What script is included with the kernel source to patch a kernel?

A. patch

B. patch-kernel

C. apply-patch

D. update-kernel

Answer: B



It is possible to patch a kernel to the newest Linux kernel version as opposed to downloading the entire source code. This choice can be beneficial for those who are not using a high-speed broadband connection. (A typical compressed kernel source file is nearly 30MB for a download time of about 10 minutes on a 512Kb DSL connection; adjust accordingly for your connection.) Whether you are patching existing sources or downloading the full source, the end results will be identical.

Patching the kernel is not a mindless task. It requires the user to retrieve all patches from her current version to the version she wants to upgrade to. For example, if you are currently running 2.6.1 (and have those sources) and want to upgrade to 2.6.8, you must retrieve the 2.6.2 and 2.6.3 patch sets, and so on. Once downloaded, these patches must be applied in succession to upgrade to 2.6.8. This is more tedious than downloading the entire source, but useful for those who keep up with kernel hacking and want to perform incremental upgrades to keep their Linux kernel as up-to-date as possible.

To patch up to several versions in a single operation, you can use the patch-kernel script located in the kernel source directory for the kernel version you currently use. This script applies all necessary version patches to bring your kernel up to the latest version.

The format for using the patch-kernel script looks like this:

patch-kernel source_dir patch_dir stopversion


Which command would you use to apply a diff file to an original?

A. patch > diff-file

B. patch < diff-file

C. patch << diff-file

D. cat diff-file >> kernel

E. cat diff-file << kernel

Answer: B


From the man pages:


patch [options] [originalfile [patchfile]]

but usually just

patch -pnum < patchfile


One of the IDE hard drives in a server is transferring data very slowly. What command must be run to enable DMA on it?

A. hdparm -d /dev/hda

B. hdparm --dma /dev/hda

C. hdparm --dma /dev/hda1

D. hdparm -d /dev/hda1

E. hdparm -d1 /dev/hda

Answer: E


hdparm provides a command line interface to various kernel interfaces supported by the Linux SATA/PATA/ SAS "libata" subsystem and the older IDE river subsystem. Many newer (2008 and later) USB drive enclosures now also support "SAT" (SCSI-ATA Command Translation) and therefore may also work with hdparm. Eg. recent WD "Passport" models and recent NexStar-3 enclosures. Some options may work correctly only with the latest kernels.

-d Disable/enable the "using_dma" flag for this drive. This option now works with most combinations of drives and PCI interfaces which support DMA and which are known to the kernel IDE driver. It is also a good idea to use the appropriate -X option in combination with -d1 to ensure that the drive itself is programmed for the correct DMA mode, although most BIOSs should do this for you at boot time. Using DMA nearly always gives the best performance, with fast I/O throughput and low CPU usage.


What happens when the Linux kernel can't mount the root filesystem when booting?

A. An error message is shown, showing which device couldn't be mounted or informing that init couldn't be found.

B. An error message is shown and the system reboots after a keypress.

C. An error message is shown and the system boots in maintenance mode.

D. An error message is shown and the administrator is asked to specify a valid root filesystem to continue the boot process.

E. An error message is shown, stating that the corresponding kernel module couldn't be loaded.

Answer: A


You have written a little startup script (/usr/local/bin/ that should automatically execute when entering runlevel 3. According to the standards, how can this best be achieved?

A. chmod 700 /usr/local/bin/; cd/etc/init.d/rc3.d/; ln -s /user/local/bin/

B. chmod 700 /usr/local/bin/; cd/etc/init.d/rc3.d/; ln -s /usr/local/bin/

C. chmod 700 /usr/local/bin/; cd/etc/init.d/rc3.d/; ln /user/local/bin/

D. chmod 700 /usr/local/bin/; cd/etc/init.d/rc3.d/; ln -s /user/local/bin/ /usr/locl/bin/

E. chmod 700 /usr/local/bin/; cp /user/local/bin/ /etc/init.d/rc3.d/

Answer: B




What command is used to create an ISO9660 filesystem that can be properly accessed from a Windows 95/98 machine?

A. mkisofs -l -o backup.iso /home/joe

B. mkisofs -J -T -r -o backup.iso /home/joe

C. mkisofs -D -T -o backup.iso /home/joe

D. mkisofs -j -T -o backup.iso /home/joe

E. mkisofs -d -T -o backup.iso /home/joe

Answer: B



-J Generate Joliet directory records in addition to regular iso9660 file names. This is primarily useful when the discs are to be used on Windows-NT or Windows-95 machines.

-T Generate a file TRANS.TBL in each directory on the CDROM, which can be used on non-Rock Ridge capable systems to help establish the correct file names.

-o filename is the name of the file to which the iso9660 filesystem image should be written.

---------------------------------- actually you can leave the "-r" option, since you wouldn't need Rock Ridge on a Windows Machine.


In order to find all library dependencies of /usr/bin/foo, which of the following statement is true?

A. Running ldconfig against /usr/bin/foo will show the required libraries

B. Running ldd against /usr/bin/foo will show the required libraries

C. It's necessary to compile the program again to check the library dependencies of foo.

D. The ls -la command has to be run in the /usr/bin directory, to show all library dependencies of foo.

E. Library dependencies are shown in the /usr/lib directory.

Answer: B


From the man pages:

ldd prints the shared libraries required by each program or shared library specified on the command line.


The user' quotas on the server were reduced from 200MB to 100MB. Besides sending emails to all users, it was requested that a message should communicate the change every time a user access the server. Which of the following is the correct method to configure this?

A. Put the message text in the /etc/login-message file

B. Put the message text in the /etc/motd file

C. Put the message text in the /etc/default/login file.

D. Put the message text in the /etc/passwd file, after all users entries.

E. There is no way to do this because the administrator has no permission to change the .bash_profile file for each user.

Answer: B


From the man pages

The contents of /etc/motd are displayed by login(1) after a successful login but just before it executes the login shell.


This message of course is not shown on GUIs!


A GRUB boot loader installed in the MBR was accidentally overwritten. After booting with a rescue CD-ROM, how can the lost GRUB first stage loader be recovered?

A. Use dd to restore a previous backup of the MBR

B. Install LILO since there is no easy way to recover GRUB

C. Running mformat will create a new MBR and fix GRUB using info from grub.conf

D. Run grub-install after verifying that grub.conf is correct.

E. Run fdisk --mbr /dev/had assuming that the boot harddisk is /dev/hda.

Answer: D


From the man pages:

Grub-install copies GRUB images into /boot/grub (or /grub on NetBSD and OpenBSD), and uses grub-setup to install grub into the boot sector.


Why is the root file system mounted read-only during boot and remounted with write permission later on?

A. Because if problems with the root file system are detected during the boot, fsck can be run, without risk of damage.

B. Because this way crackers cannot collect information about root with boot sniffers

C. To avoid writing to the disk, unless the root password is known.

D. To avoid other operating systems overwriting the Linux root partition

E. Because the disk has its own write protection that cannot change by the operating system.

Answer: A


Following the instructions contained in the README file of an application, the make command was executed but the following message was displayed on the screen:

Make: *** No targets specified and no makefile found. Stop.

Which are the TWO possible causes for this problem?

A. The make command is being executed in the wrong location.

B. The user has no write permission to the Makefile, so he cannot execute the make command correctly.

C. The make command was executed in the right place but the command to generate the Makefile was not properly executed.

D. The make command is not installed in the system.

E. The development libraries needed by make are not installed on the system.

Answer: A, C


It is possible to configure kernel parameters at runtime (e.g. the maximum size of the shared memory segment (shmmax)). In which TWO ways can this be changed to 2GB (2147483648 Bytes) on a running system?

A. Edit /etc/shmmax and set the parameter to 2147483648.

B. sysctl shmmax=2147483648.

C. sysctl kernel.shmmax=2147483648

D. echo 2147483648 > /proc/sys/kernel/shmmax

E. export kernel.shmmax=2147483648

Answer: C, D


To make a system backup, the simplest and fastest way is to use the tar command. Select the correct alternative below that shows the three tar parameters that create, list and expand a tar file respectively.

A. --create --list --extract

B. --compose --list --expand

C. -c -t -e

D. -c -l -x

Answer: A


From the man pages:

-c, --create create a new archive

-t, --list list the contents of an archive

-x, --extract, --get extract files from an archive


A Linux machine freezes during boot. To boot directly to a shell prompt so that editing of files and manual starting of services is possible which command line must be passed to the kernel for the boot process?

A. init=/bin/bash

B. 1

C. runlevel=1

D. sh

E. /bin/sh

Answer: A



In Linux systems, with most modern bootloaders (such as LILO or GRUB), users can change which process the kernel spawns at the end of its initialization from the normal default of /sbin/init. This is generally done by typing init=/foo/bar at the bootloader's prompt. Appending init=/bin/bash, for example, will bring up a single root shell, without a password.


Which ONE of the following wireless tools can be used to check the wireless network link quality?

A. iwconfig

B. iwlink

C. iwscan

D. iwifi

Answer: A




A network client has an ethernet interface configured with an IP address in the subnet This subnet has a router, with the IP address, that connects this subnet to the Internet. What needs to be done on the client to enable it to use the router as its default gateway?

A. Run route add default gw eth1.

B. Run route add gw eth1.

C. Run ifconfig eth0 defaultroute

D. Add "defaultroute" to /etc/resolv.conf.

E. Run route add defaultgw= if=eth0.

Answer: A


From the man pages:

route add default gw mango-gw adds a default route (which will be used if no other route matches). All packets using this route will be

gatewayed through "mango-gw". The device which will actually be used for that route depends on how we can reach "mango-gw" - the static route to "mango-gw" will have to be set up before.


What is the command to add another IP address to an interface that already has (at least) one IP address?

A. ifconfig eth0:1

B. ifconfig eth0

C. ipconfig eth0:1

D. ipconfig eth0

E. ifconfig eth0:sub1

Answer: A, E


From the man pages:

ifconfig - configure a network interface

The interface is usually a driver name followed by a unit number, for example eth0 for the first Ethernet interface. If your kernel supports alias interfaces, you can specify them with eth0:0 for the first alias of eth0.

You can use them to assign a second address.


Which of these tools can provide the most information about DNS queries?

A. dig

B. nslookup

C. host

D. named-checkconf

E. named-checkzone

Answer: A


dig - DNS lookup utility

nslookup - query Internet name servers interactively

Host - DNS lookup utility

Named-checkconf - named configuration file syntax checking tool

Named-checkzone - zone file validity checking tool


What command must be used to create an ext3 file-system?

A. mkext3fs

B. mkjfs

C. mke3fs

D. mke2fs

E. mkext2fs

Answer: D


Also: mkfs -t ext3 or mkfs.ext3 if you call mke2fs you actually need option -J to enable journalling otherwise ext2 will be used.


What needs to be done to enable 32 bit I/O transfer mode for (E)IDE disks, on a system running a 2.4 series Linux kernel?

A. The Linux kernel must be recompiled.

B. The sysctl utility must be used.

C. The hdparm utility must be used.

D. This feature isn't supported in 2.4 series kernels.

E. This feature is enabled by default in 2.4 series kernels

Answer: C



hdparm provides a command line interface to various hard disk ioctls supported by the stock Linux ATA/IDE device driver subsystem. Some options may work correctly only with the latest kernels.

-c Query/enable (E)IDE 32-bit I/O support. A numeric parameter can be used to enable/disable 32-bit I/O support: Currently supported values include 0 to disable 32-bit I/O support, 1 to enable 32-bit data transfers, and 3 to enable 32-bit data transfers with a special sync sequence required by many chipsets. The value 3 works with nearly all 32-bit IDE chipsets, but incurs slightly more overhead. Note that "32-bit" refers to data transfers across a PCI or VLB bus to the interface card only; all (E)IDE drives still have only a 16-bit connection over the ribbon cable from the interface card.


DNSSEC is used for?

A. Encrypted DNS queries between nameservers.

B. Cryptographic authentication of DNS zones.

C. Secondary DNS queries for local zones.

D. Defining a secure DNS section.

E. Querying a secure DNS section.

Answer: B



DNSSEC was designed to protect Internet resolvers (clients) from forged DNS data, such as that created by DNS cache poisoning. All answers in DNSSEC are digitally signed. By checking the digital signature, a DNS resolver is able to check if the information is identical (correct and complete) to the information on the authoritative DNS server.


The following is an excerpt from the output of tcpdump -nli eth1 'udp':

13:03:17.277327 IP > 43653+ A? (25)

13:03:17.598624 IP > 43653 1/0/0 A (41)

Which network service or protocol was used?






Answer: D

Explanation: shows that we connect to Port 53 and /etc/services specifies port 53 as DNS.

# cat /etc/services

Domain 53/tcp # name-domain server

Domain 53/udp here is another example of tcpdump catching a DNS request and response:

11:17:44.585523 IP > 7880+ A? (31)

11:17:44.621611 IP > 7880 8/0/0 CNAME, CNAME, A, A, A, A, A, A (175)


During which stage of the boot process would this message be seen?

ide_setup: hdc=ide-scsi

A. Daemon initialization and setup.

B. Boot loader start and hand off to kernel.

C. Hardware initializiation and setup.

D. Kernel loading.

Answer: D



In the Kernel-Loading phase it re-initializes parallel ports, serial ports and all the on-board controllers like USB, IDE, SCSI, Serial, parallel, timers, RTC etc. These startup drivers are also called BSP drivers or Board Support Drivers.


After configuring a new 2.4 series kernel, all dependencies, such as included files, need to be created. How can this be achieved?

A. make dependencies

B. make clean

C. make mrproper

D. make dep

E. make test

Answer: D


/usr/src/linux# make clean

If you've already built the system and are making minor changes, not wanting to re-compile all the objects again, skip this step. If you want to be a purist and make sure you're starting absolutely fresh, do this step./usr/src/linux# make mrproper

This completely cleans out your binary directories. I only do this if I've really screwed something up. Note that this deletes your .config file, so you might want to rename it first! I hardly ever do this. /usr/src/linux# make dep This determines all the header file dependencies. Do this whenever you've made a change to the configuation.


Considering the following kernel IP routing table now, which of the following commands must be remove the route to the network

Kernel IP routing table

Destination Gateway Genmask Flags Metric Ref Use Iface UH 0 0 0 ppp0 U 0 0 0 eth0 U 0 0 0 eth1 UG 0 0 0 eth1 U 0 0 0 lo UG 0 0 0 ppp0

A. route del

B. route del

C. route del -net

D. route del gw

E. route del -net

Answer: C


Either specify net in CIDR notation or specify parameter netmask


Some users are unable to connect to specific local hosts by name, while accessing hosts in other zones works as expected. Given that the hosts are reachable by their IP addresses, which is the default log file that could provide hints about the problem?

A. /var/named/log

B. /var/lib/named/dev/log

C. /var/log/bind_errors

D. /var/log/bind/errors

E. /var/log/messages

Answer: E


BIND uses syslogd before a valid logging clause is available so named.conf parse errors and other information will appear in /var/log/messages (depending on syslog.conf) prior to, or in the absence of, a valid logging clause.

On Ubuntu Systems this is equal to /var/log/syslog.


If the command arp -f is run, which file will be read by default?

A. /etc/hosts

B. /etc/ethers

C. /etc/arp.conf

D. /etc/networks

E. /var/cache/arp

Answer: B


from the man pages:

arp - manipulate the system ARP cache

-f filename, --file filename

Similar to the -s option, only this time the address info is taken from file filename. This can be used if ARP entries for a lot of hosts have to be set up. The name of the data file is very often /etc/ethers, but this is not official. If no filename is specified /etc/ethers is used as default.

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