EX200 Practice Test 28 — 15 Questions

Question 1

A system has two 500GB disks in a RAID1 (mirror) using mdadm. One disk fails. After replacement, what is the correct procedure to restore redundancy?

Accepted Answer

Use sfdisk to copy partition table from /dev/sda to /dev/sdb, then 'mdadm --manage /dev/md0 --add /dev/sdb1'. When replacing a failed disk in a RAID1 array managed by mdadm, the new disk must have a partition table that matches the surviving disk. Using sfdisk to copy the partition table from /dev/sda to /dev/sdb ensures that the partition layout (e.g., partition type 0xFD for Linux RAID autodetect) is identical, which is required before adding the partition (e.g., /dev/sdb1) to the array with mdadm --manage --add. Simply adding the raw disk without a proper partition table would fail because mdadm expects a partition with the correct RAID superblock and partition type.

Answer

Run 'mdadm --manage /dev/md0 --add /dev/sdb'

Answer

Remove the failed disk with 'mdadm /dev/md0 --fail /dev/sdb1' then add new.

Answer

Run 'mdadm --assemble --scan' to rebuild the array automatically.

Question 2

Which two commands can be used to display the contents of a compressed .tar.gz archive without extracting it? (Choose two)

Accepted Answer

tar -tzf archive.tar.gz. `tar -tzf` lists the contents of a gzip-compressed tar archive without extracting it. The `-t` flag tells tar to list the table of contents, `-z` handles the gzip decompression on the fly, and `-f` specifies the archive file. This is the standard way to inspect a .tar.gz file's contents without extraction.

Answer

gzcat archive.tar.gz

Answer

less archive.tar.gz

Answer

tar -xf archive.tar.gz

Question 3

Which TWO commands can be used to view the contents of a compressed file named 'data.log.gz' without decompressing it permanently? (Choose exactly two.)

Accepted Answer

zcat data.log.gz. B is correct because `zcat` reads the contents of a gzip-compressed file and outputs them to standard output without permanently decompressing the file. It is functionally equivalent to `gunzip -c` and is the standard tool for viewing compressed text files in place.

Answer

gunzip data.log.gz

Answer

gzip -d data.log.gz

Answer

bzcat data.log.gz

Question 4

Which THREE commands are required to create a logical volume named lv_data of size 10G in volume group vg_data, format it as XFS, and mount it at /mnt/data?

Accepted Answer

lvcreate -L 10G -n lv_data vg_data. The `lvcreate -L 10G -n lv_data vg_data` command creates a logical volume named lv_data with a size of 10 GB within the volume group vg_data. This is the standard LVM command for creating logical volumes, where `-L` specifies the size and `-n` specifies the name.

Answer

vgcreate vg_data /dev/sde1

Answer

pvcreate /dev/sde1

Question 5

The administrator wants to create a new ext4 file system on /dev/sdb1 with a block size of 1024 bytes. Which command should be used?

Accepted Answer

mkfs.ext4 -b 1024 /dev/sdb1. The `-b` flag in `mkfs.ext4` specifies the block size in bytes. To create an ext4 filesystem with 1024-byte blocks on /dev/sdb1, the command `mkfs.ext4 -b 1024 /dev/sdb1` is used. This is the standard syntax for setting the logical block size when formatting an ext4 filesystem.

Answer

mkfs.ext4 -B 1024 /dev/sdb1

Answer

mkfs.ext4 -s 1024 /dev/sdb1

Answer

mkfs.ext4 --block-size 1024 /dev/sdb1

Question 6

A logical volume 'lv_share' in volume group 'vg_share' has no free extents. The administrator needs to increase the size of '/dev/vg_share/lv_share' by 5 GB. There is another logical volume 'lv_archive' in the same volume group that has 10 GB free space within its filesystem. What must the administrator do to allocate space from 'lv_archive' to 'lv_share'?

Accepted Answer

Reduce the filesystem on 'lv_archive' with resize2fs, then reduce the logical volume with lvreduce, then extend 'lv_share'.. You must first shrink the filesystem on 'lv_archive' using resize2fs (or e2fsck -f / resize2fs) to free space within the filesystem, then reduce the logical volume with lvreduce to release the underlying physical extents back to the volume group. Only after those steps can you extend 'lv_share' with lvextend and then resize its filesystem. This sequence ensures data integrity and avoids filesystem corruption.

Answer

Shrink the filesystem on 'lv_archive' to free space, then use vgsplit to move the space to 'lv_share'.

Answer

Use lvreduce directly on 'lv_archive' without changing the filesystem, then lvextend on 'lv_share'.

Answer

Use lvresize to reduce 'lv_archive' and extend 'lv_share' in one command.

Answer

Add a new physical volume to the volume group instead.

Question 7

To enforce that user passwords expire every 90 days and users are warned 7 days before expiration, which command sets these policies for user 'john'?

Accepted Answer

chage -M 90 -W 7 john. The `chage -M 90 -W 7 john` command sets the maximum number of days a password is valid (password aging) to 90 days via the `-M` flag, and the `-W` flag sets the warning period to 7 days before expiration. The `chage` command is the standard tool in Red Hat Enterprise Linux for modifying user password aging information stored in `/etc/shadow`.

Answer

chage -m 90 -W 7 john

Answer

usermod -e 90 -f 7 john

Answer

passwd -x 90 -w 7 john

Question 8

An administrator needs to create a 10GB logical volume named 'mylv' in an existing volume group 'vg1', format it with XFS, and mount it at /mnt/data. Which set of commands achieves this correctly?

Accepted Answer

lvcreate -n mylv -L 10G vg1 && mkfs.xfs /dev/vg1/mylv && mount /dev/vg1/mylv /mnt/data && echo "/dev/vg1/mylv /mnt/data xfs defaults 0 0" >> /etc/fstab. It uses the proper `lvcreate` syntax with `-n` for name and `-L` for size, creates the logical volume `/dev/vg1/mylv`, formats it with XFS, mounts it, and appends the correct fstab entry using `>>` to avoid overwriting existing entries. The device path `/dev/vg1/mylv` is the standard LVM device mapper path for a logical volume named 'mylv' in volume group 'vg1'.

Answer

lvcreate -n mylv -L 10G vg1 && mkfs.xfs /dev/vg1/mylv && mount /dev/vg1/mylv /mnt/data && blkid /dev/vg1/mylv >> /etc/fstab

Answer

lvcreate -n mylv -L 10G vg1 && mkfs.xfs /dev/vg1/mylv && mount /dev/vg1/mylv /mnt/data && echo "/dev/vg1/mylv /mnt/data xfs defaults 0 0" > /etc/fstab

Answer

lvcreate -n mylv --size 10G vg1 && mkfs.xfs /dev/mylv && mount /dev/mylv /mnt/data && echo "/dev/mylv /mnt/data xfs defaults 0 0" >> /etc/fstab

Question 9

An administrator wants to ensure that a file system is automatically mounted at boot. Which file should be edited?

Accepted Answer

/etc/fstab. The /etc/fstab file is the standard configuration file that defines how disk partitions, block devices, and remote filesystems should be mounted into the filesystem tree, including options for automatic mounting at boot time. The system reads this file during the boot process (via systemd or the traditional mount -a command) to mount all filesystems listed with the 'auto' or nofail option.

Answer

/etc/rc.local

Answer

/boot/grub2/grub.cfg

Answer

/etc/mtab

Question 10

A junior administrator needs to create a new Ext4 file system on the device /dev/sdb1. Which command should be used?

Accepted Answer

mkfs.ext4 /dev/sdb1. The `mkfs.ext4` command is the standard utility for creating an ext4 filesystem on a block device. It formats the partition with the ext4 journaling filesystem, writing the superblock, inode table, and journal metadata. Option D is correct because it directly invokes the mke2fs program with the ext4 filesystem type.

Answer

fdisk /dev/sdb1

Answer

parted /dev/sdb1

Answer

tune2fs /dev/sdb1

Answer

fsck /dev/sdb1

Question 11

An administrator needs to add a 2GB swap partition to an existing disk (/dev/sdc) that already has one partition. The administrator creates a second primary partition using fdisk and sets the type to Linux swap (82). Which command completes the setup to enable swap?

Accepted Answer

mkswap /dev/sdc2 && swapon /dev/sdc2. After creating the partition with fdisk and setting the type to 82 (Linux swap), the partition must be formatted as a swap area using `mkswap` before it can be activated. The `swapon` command then enables the swap space. Option C correctly chains `mkswap /dev/sdc2` to initialize the swap signature and `swapon /dev/sdc2` to activate it.

Answer

swapon /dev/sdc2

Answer

mkfs.swap /dev/sdc2 && swapon /dev/sdc2

Answer

mkswap /dev/sdc && swapon /dev/sdc

Question 12

A system is experiencing high CPU usage. The administrator suspects a process is stuck in an infinite loop. Which command can be used to identify the most CPU-intensive process in real-time?

Accepted Answer

top. The `top` command provides a real-time, dynamic view of system processes, sorted by CPU usage by default. It continuously refreshes, making it ideal for identifying the most CPU-intensive process as it runs, which directly addresses the scenario of a suspected infinite loop causing high CPU usage.

Answer

lsof

Answer

ps aux

Answer

strace

Question 13

A script needs to read every line from a file and execute a command on each line. Which code block is correct and handles whitespace correctly?

Accepted Answer

while IFS= read -r line; do echo "$line"; done < file.txt. It uses `IFS=` to preserve leading/trailing whitespace and `-r` to prevent backslash interpretation, ensuring each line is read exactly as it appears in the file. The `< file.txt` redirect feeds the file line by line into the `while` loop, which is the standard and safe method for line-by-line processing in Bash.

Answer

while IFS=$'
' read line; do echo "$line"; done <<< file.txt

Answer

while read line; do echo $line; done < file.txt

Answer

for line in $(cat file.txt); do echo $line; done

Question 14

A junior admin needs to ensure that the 'apache' user (UID 48) cannot log in via SSH or console. Which command achieves this?

Accepted Answer

usermod -s /sbin/nologin apache. Setting the user's login shell to `/sbin/nologin` prevents the user from obtaining an interactive shell via SSH or console login. When the user attempts to log in, the system executes `/sbin/nologin`, which prints a polite message and exits immediately, effectively denying shell access while leaving other services (e.g., Apache) functional.

Answer

passwd -l apache

Answer

chage -l apache

Answer

usermod -e 1 apache

Question 15

A system administrator needs to ensure that a user named 'bob' can access a shared directory '/data' owned by group 'developers'. The directory has permissions 2775 and is owned by root:developers. Bob is a member of the 'developers' group. However, when Bob tries to create a file in '/data', it fails with 'Permission denied'. What is the most likely cause?

Accepted Answer

The directory has incorrect SELinux context. The directory '/data' has permissions 2775, which grants read, write, and execute to the group 'developers'. Bob is a member of 'developers', so standard Unix permissions should allow him to create files. However, the failure with 'Permission denied' despite correct group membership and permissions strongly indicates that SELinux is enforcing a policy that denies Bob write access. The most likely cause is that the directory lacks the correct SELinux context (e.g., `default_t` instead of a type like `public_content_rw_t` or a context that allows write operations).

Answer

Bob's umask is set to 0077

Answer

The setgid bit is not set

Answer

Bob's primary group is not developers