EX200 Practice Test 2 — 10 Questions

Question 1

A developer needs to search for the string 'ERROR' in all files under /var/log, but wants to exclude files ending with '.gz'. Which command is correct?

Accepted Answer

grep -r --exclude='*.gz' 'ERROR' /var/log. `grep -r` performs a recursive search through all files under /var/log, and the `--exclude='*.gz'` option tells grep to skip any files matching the glob pattern '*.gz'. This combination ensures that only non-compressed log files are searched for the string 'ERROR', meeting the requirement exactly.

Option B uses `-R` instead of `-r`. In GNU grep, `-R` implies `--dereference-recursive`, which follows symbolic links into other directories. This could lead to searching outside `/var/log` if any symlinks point elsewhere, making it less precise for the stated requirement. While `-r` and `-R` are often conflated, `-R` is not equivalent to `-r` when symlinks are present, and the standard recursive option is `-r`. Therefore, B is incorrect.

Answer

grep -R --exclude='*.gz' 'ERROR' /var/log

Answer

grep -l 'ERROR' /var/log/*.gz

Answer

grep -v '*.gz' -r 'ERROR' /var/log

Question 2

A Red Hat Enterprise Linux server has been configured with a custom repository for offline updates. The administrator runs 'yum repolist' and the custom repository is not listed. Which command should be used to verify that the repository configuration file is valid and located in the correct directory?

Accepted Answer

cat /etc/yum.repos.d/custom.repo. The most direct way to verify that a repository configuration file is valid and located in the correct directory is to check its presence and syntax using 'cat /etc/yum.repos.d/custom.repo'. The repository configuration files must reside in /etc/yum.repos.d/ and have a .repo extension; if the file is missing or malformed, 'yum repolist' will not list the repository. This command simply reads the file, allowing the administrator to confirm its location and inspect its contents for errors.

Answer

yum repoinfo

Answer

yum check-repo

Answer

yum-config-manager --dump

Question 3

The administrator wants to mount a new filesystem on /dev/sdb1 with the label 'backup' and mount it at /mnt/backup. Which commands achieve this?

Accepted Answer

mkfs.xfs /dev/sdb1 && xfs_admin -L backup /dev/sdb1 && mount -L backup /mnt/backup. Both options B and C correctly create an XFS filesystem with the label 'backup' on /dev/sdb1 and mount it to /mnt/backup. Option B uses mkfs.xfs, then sets the label with xfs_admin, then mounts by label (mount -L works without fstab). Option C creates the filesystem with the label in one step and mounts by device path. Options A and D are incorrect: A includes an unnecessary parted command and uses ext4? Actually A creates an XFS partition but then mounts? Wait A: parted ... mkpart primary xfs ... && mkfs.xfs -L backup /dev/sdb1. It doesn't mount, so incomplete. D uses ext4, not XFS. Thus B and C are both valid.

Answer

parted /dev/sdb mkpart primary xfs 0% 100% && mkfs.xfs -L backup /dev/sdb1

Answer

mkfs.ext4 -L backup /dev/sdb1 && echo '/dev/sdb1 /mnt/backup ext4 defaults 0 0' >> /etc/fstab

Question 4

Refer to the exhibit. A container named 'db' is running on the host. An administrator runs `podman inspect db` and sees the above output snippet. What can be concluded about the container's network configuration?

Accepted Answer

The container's port 3306 is bound to all host interfaces.. The output snippet from `podman inspect db` shows `"Ports": {"3306/tcp": [{"HostIp": "0.0.0.0", "HostPort": "3306"}]}`. This indicates that the container's port 3306 is mapped to port 3306 on all host interfaces (0.0.0.0), which is the default bridge networking port binding behavior. Therefore, option C is correct.

Answer

The container is using host networking mode.

Answer

The container cannot be reached from other containers.

Answer

The container is using bridge networking with a static IP.

Question 5

A database server experiences high disk I/O wait times. The administrator runs 'iostat -x 1' and sees that the avgqu-sz for /dev/sda is 25 and await is 200 ms. The disk is a single 7200 RPM SATA drive. Which action is most likely to improve performance?

Accepted Answer

Replace the drive with an SSD or add additional drives in RAID 10. The high avgqu-sz (25) and await (200 ms) indicate the single 7200 RPM SATA drive is saturated, as its maximum IOPS is typically around 75-100 random I/O operations per second. Replacing it with an SSD (which can handle thousands of IOPS) or adding drives in RAID 10 (which increases IOPS through parallelism) directly addresses the hardware bottleneck. No software tuning can overcome the physical limitations of a single spinning disk under heavy I/O load.

Answer

Increase the read-ahead buffer using blockdev --setra

Answer

Change the I/O scheduler from CFQ to noop

Answer

Run 'fsck -f' on the filesystem to check for fragmentation

Question 6

A system administrator has created a new group named 'ops'. The administrator wants to add the existing user 'alice' to this group as a supplementary group without affecting her current group memberships. Which command should be used?

Accepted Answer

usermod -aG ops alice. The `-a` (append) flag combined with `-G` (supplementary groups) in `usermod` adds the user 'alice' to the 'ops' group without removing her from any existing supplementary groups. Without `-a`, the `-G` flag alone would replace the user's current supplementary group list with only the specified groups, which would remove her from any other groups she already belongs to.

Answer

usermod -G ops alice

Answer

groupadd ops alice

Answer

usermod -g ops alice

Question 7

Refer to the exhibit. An administrator wants to mount /dev/sdc1 on /mnt/storage. What must be done first?

Accepted Answer

Create a partition on /dev/sdc. The exhibit shows that /dev/sdc has no partition table (it is a raw disk). Before you can mount a filesystem on /dev/sdc1, you must first create a partition on /dev/sdc using a tool like fdisk or parted. Without a partition, the block device /dev/sdc1 does not exist, so any mount attempt would fail with a 'no such device' error.

Answer

Mount /dev/sdc directly

Answer

Add an entry to /etc/fstab

Answer

Run mkfs.xfs /dev/sdc1

Question 8

An administrator wants to mount an existing ext4 filesystem from /dev/sdb1 to /mnt/data at boot time. What entry should be added to /etc/fstab?

Accepted Answer

/dev/sdb1  /mnt/data  ext4  defaults  0  0. It specifies the correct device (/dev/sdb1), the correct mount point (/mnt/data), the correct filesystem type (ext4), and the correct mount options (defaults) for an ext4 filesystem to be mounted at boot. The /etc/fstab entry must include all six fields in order: device, mount point, filesystem type, options, dump, and pass.

Answer

/dev/sdb1  /mnt/data  xfs  defaults  0  0

Answer

LABEL=data  ext4  defaults  0  0

Answer

/dev/sdb1  /data  ext4  defaults  0  0

Question 9

A system administrator is configuring a new RHEL 9 server with two 500GB SSDs. The requirement: create a 200GB XFS filesystem for /srv/data that is resilient to disk failure. The admin decides to create a RAID 1 (mirror) using mdadm with partitions on each disk: /dev/sda1 and /dev/sdb1, each 200GB. He creates the partitions with fdisk, then runs: mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1. The array is created and synced. He then creates a physical volume, volume group, and logical volume on top of /dev/md0, formats with XFS, and mounts. Later, a disk fails. After replacing the failed disk, he recreates the partition with identical size and runs: mdadm /dev/md0 --add /dev/sdb1. The command fails with 'Device /dev/sdb1 is busy'. What is the most likely cause?

Accepted Answer

The kernel still sees the old partition table; need to run partprobe to reread the partition table.. After replacing a failed disk and recreating the partition, the kernel's in-memory partition table still reflects the old state. The `mdadm --add` command fails with 'Device busy' because the kernel sees the old partition layout and may still hold references to the old partition. Running `partprobe` (or `partx -a`) forces the kernel to reread the partition table from the disk, clearing the stale state and allowing the new partition to be added to the RAID array.

Answer

The replacement disk was not initialized with an mdadm superblock before adding.

Answer

The /dev/md0 array is still in a clean state and does not need the disk yet.

Answer

The /dev/sdb1 partition is already part of another md array.

Question 10

A server uses firewalld with the default zone set to 'drop'. SSH is allowed only for the 192.168.1.0/24 subnet via a rich rule in the 'internal' zone. After a reboot, SSH connections from that subnet are refused. What is the most likely cause?

Accepted Answer

The network interface is not assigned to the 'internal' zone.. After a reboot, firewalld applies the default zone to all interfaces not explicitly assigned to another zone. Since the rich rule allowing SSH from 192.168.1.0/24 is defined in the 'internal' zone, the network interface must be assigned to that zone for the rule to take effect. If the interface is not assigned (e.g., it remains in the default 'drop' zone), all incoming traffic, including SSH from the allowed subnet, is dropped by default.

Answer

The subnet 192.168.1.0/24 is not a valid source for rich rules.

Answer

The rich rule was not made permanent.

Answer

The SSH service is not enabled in the default zone.