010-160 Hard Questions — 25 Difficult Questions

Question 1

A hospital's IT department wants to adopt a Linux-based electronic records system. Legal counsel insists that the hospital be able to audit and modify the source code to meet patient-data regulations, and that any redistributed improvements remain under the same freedoms. Which licensing approach best satisfies counsel's requirements?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

A copyleft license such as the GNU GPL, because derivative works must be distributed under the same license terms.. Counsel wants both the ability to audit and modify source code and the guarantee that redistributed improvements stay open. A copyleft license such as the GNU GPL provides exactly those rights and obligations. Permissive and public domain licenses allow proprietary relicensing downstream, and escrow grants only conditional access without modification rights.

Answer

A proprietary license with a source-code escrow agreement, because escrow guarantees permanent access to the code.

Answer

A public domain dedication, because it removes all restrictions and lets the hospital do anything it wants.

Answer

A permissive license such as MIT, because it allows modification without any redistribution conditions.

Question 2

A junior administrator is asked to verify whether a newly installed application is truly open source. The application's documentation states that the source code is available but forbids modification and redistribution. Which statement best evaluates this claim?

Accepted Answer

It does not qualify as open source because modification and redistribution are prohibited.. Open source requires more than visible source code; the license must permit modification and redistribution. Because this application forbids both, it fails the Open Source Initiative definition and should be treated as source-available or proprietary despite its published code.

Answer

It qualifies as open source because users can read and audit the code.

Answer

It qualifies as open source because the source code is publicly available.

Answer

It qualifies as open source if the vendor provides the source code on request.

Question 3

A developer runs a program that writes progress messages to standard error and results to standard output. They want to save only the results to results.txt while still seeing progress messages on the terminal. Which redirection accomplishes this?

Accepted Answer

program > results.txt. Only the plain `>` redirection sends standard output to the file while leaving standard error attached to the terminal. Operators like `2>`, `&>`, and `> file 2>&1` either redirect the wrong stream or merge both streams, which would hide progress messages from the terminal.

Answer

program 2> results.txt

Answer

program > results.txt 2>&1

Answer

program &> results.txt

Question 4

A Linux administrator is reviewing how environment variables affect command execution. Which TWO of the following statements about environment variables are correct? (Choose two.)

Accepted Answer

Environment variables are always inherited by child processes unless explicitly unset.. PATH determines where the shell looks for executables, and environment variables are inherited by child processes by default. These two properties are central to how commands are located and how settings propagate in a Linux session. The other statements misidentify HOME and PS1 and incorrectly restrict variable setting to root, so they are not correct.

Answer

Environment variables can only be set by the root user.

Answer

The PS1 variable controls the system's primary network interface.

Answer

The HOME variable stores the system's hostname.

Question 5

You want to execute two commands sequentially, but only if the first command succeeds. Which operator is used?

Accepted Answer

&&. The && operator is the logical AND control operator in Bash and other POSIX shells. It executes the command on the right only if the command on the left exits with a status of 0 (success). This is the standard way to chain commands with a success dependency, such as 'make && make install'.

Answer

;

Answer

||

Answer

|

Question 6

A Linux system administrator notices that the /var/log directory is filling up quickly. They want to find the largest files within that directory tree to identify what is consuming space. Which command will accomplish this?

Accepted Answer

du -ah /var/log | sort -rh | head -n 10. The combination of du -ah, sort -rh, and head -n 10 provides a sorted list of the largest files and directories under /var/log. This allows the administrator to quickly identify space hogs. Other commands either filter by size, limit to one directory level, or show filesystem-wide usage, which are not as effective for this specific task.

Answer

df -h /var/log

Answer

ls -lS /var/log

Answer

find /var/log -type f -size +100M

Question 7

Why do many enterprise Linux distributions choose to delay the inclusion of the absolute latest kernel version?

Accepted Answer

Because they prioritize stability and extensive testing to ensure production uptime.. Enterprise distributions such as RHEL, SLES, and Ubuntu LTS deliberately backport fixes to older, well-tested kernels rather than shipping the newest upstream release. This prioritizes stability, hardware/driver compatibility, and predictable behavior so that production workloads and certified ISV applications continue to run without regression. Extensive QA, regression testing, and vendor certification cycles take time, which is why enterprise kernels lag mainline.

Answer

Because the latest kernel is always incompatible with proprietary software.

Answer

Because they are legally required to wait 12 months.

Answer

Because they lack the technical staff to compile new kernels.

Question 8

A Linux administrator needs to grant a contractor temporary read and write access to a project directory without adding the contractor's account to a shared group or changing ownership of existing files. Which approach best meets this requirement while following standard Linux permission practice?

Accepted Answer

Use setfacl to add an access ACL entry granting the contractor rw on the directory and its contents.. POSIX access control lists allow permissions to be assigned to specific named users and groups beyond the three traditional classes. Using setfacl to add an entry for the contractor grants exactly the needed read and write rights on the project directory without disturbing group membership or ownership, and the entry can later be revoked with setfacl -x to end access.

Answer

Set the directory permissions to 777 so the contractor can read and write regardless of ownership.

Answer

Change the directory's group to the contractor's primary group and set permissions to 770.

Answer

Create a hard link to the directory inside the contractor's home directory.

Question 9

A Linux administrator is working in a directory with many files and wants to identify files by their type and permissions without opening them. Which TWO commands can provide this information? (Choose two.)

Accepted Answer

ls -l. To identify file type and permissions without opening files, ls -l provides permissions and type indicators, while file determines the content type. Together they cover both needs. cat and less open file contents, which is not desired, and stat focuses on metadata like permissions but does not classify content type as file does. Thus, ls -l and file are the two appropriate commands.

Answer

stat

Answer

cat

Answer

less

Question 10

Which TWO statements regarding the 'umask' command are correct?

Accepted Answer

It sets default permissions for new files.. Option B is correct because umask defines the default permission bits that are removed when a new file or directory is created, so it directly sets the default permissions for new files (e.g., a umask of 022 yields 644 for files and 755 for directories). Option E is correct because umask works by masking, or clearing, permission bits from the base creation mode (666 for files, 777 for directories) so those bits are not set on newly created files. Option A is wrong because any user can set their own umask, not just root. Option C is wrong because umask is a shell/process attribute typically set in shell profiles like /etc/profile or ~/.bashrc, not stored in /etc/shadow, which holds password hashes. Option D is wrong because umask only affects files created after it is set; it does not retroactively change permissions on existing files.

Answer

It can only be set by root.

Answer

It is stored in /etc/shadow.

Answer

It applies to existing files immediately.

Question 11

A user's account has been compromised. Which command is the most effective way to lock the user account immediately while preserving their files?

Accepted Answer

usermod -L jdoe. `usermod -L jdoe` locks the account by prepending an exclamation mark (!) to the password hash in /etc/shadow, immediately preventing password-based logins while leaving the user's home directory, files, UID, and group memberships fully intact. This is the standard, reversible administrative action for a compromised account because it disables authentication without destroying data or ownership.

Answer

userdel jdoe

Answer

killall -u jdoe

Answer

chsh -s /bin/false jdoe

Question 12

Which TWO of the following help manage compressed archive contents?

Accepted Answer

gzip. Option C, gzip, is correct because it is the standard GNU/Linux compression utility that compresses and decompresses files (creating .gz archives) and can also list compression information with gzip -l, directly managing compressed archive contents. Option E, tar, is correct because it is the archiving utility that bundles multiple files and directories into a single archive and, when combined with compression options such as -z (gzip), -j (bzip2), or -J (xz), creates and extracts compressed archives like .tar.gz, making it a primary tool for managing compressed archive contents. Option A, find, is incorrect because it searches the filesystem for files matching criteria such as name, size, or permissions; it does not compress, decompress, or manipulate archive contents. Option B, cat, is incorrect because it concatenates and displays file contents to standard output and has no archive or compression management capability. Option D, grep, is incorrect because it searches text patterns within files and, while it can search inside uncompressed streams, it does not create, extract, or otherwise manage compressed archives.

Answer

find

Answer

cat

Answer

grep

Question 13

An administrator needs to monitor network traffic in real-time on a specific interface. Which tool is commonly used to capture and display packets?

Accepted Answer

tcpdump. tcpdump is the classic command-line packet capture tool that reads frames from a network interface via libpcap and displays them in real time or writes them to a pcap file. It supports BPF filter expressions to narrow captured traffic, making it ideal for live monitoring on a specific interface (e.g., tcpdump -i eth0). This matches the requirement to capture and display packets.

Answer

netstat

Answer

iptables

Answer

nmap

Question 14

Which THREE of the following are types of manual page sections?

Accepted Answer

User commands (1). The Linux manual pages are organized into numbered sections, and the three options marked correct are genuine section types: B 'User commands (1)' is section 1, which documents executable programs and shell commands users can run; C 'System calls (2)' is section 2, which documents the kernel system-call interface used by programs such as open(2) and read(2); and D 'File formats (5)' is section 5, which documents file formats and conventions such as /etc/passwd(5) and proc(5). The unmarked options do not belong: A 'Network protocols (10)' is not a manual section (section 10 does not exist in the standard man-pages layout), and E 'Kernel hardware (20)' is not a manual section either (section 20 is not a standard section; hardware-related pages typically appear in section 4, 'Devices and special files').

Answer

Network protocols (10)

Answer

Kernel hardware (20)

Question 15

You are trying to find the location of a binary file, specifically the 'ls' command. Which command is best suited for this?

Accepted Answer

which. The which command searches the directories listed in the PATH environment variable and returns the full path of the executable that would run when the command is invoked. For locating the 'ls' binary that the shell will actually execute, which is the precise tool. It respects aliases and PATH order, making it ideal for resolving command locations.

Answer

find

Answer

locate

Answer

whereis

Question 16

Which command displays the first 5 lines of a file?

Accepted Answer

head -5 file. -n 5 specifies the number of lines for the head utility.

Answer

tail -n 5 file

Answer

cat -n 5 file

Question 17

Which command would you use to list files in long format, sorted by modification time, with the newest files appearing first?

Accepted Answer

ls -ltr. The -l (long), -t (time), and -r (reverse) flags together achieve this.

Answer

ls -lt

Answer

ls -lr

Answer

ls -Rlt

Question 18

You are troubleshooting a network issue where a Linux server cannot reach an external website. The ping command to the gateway succeeds, but pinging the website IP fails. Which configuration file should you check to ensure the server can resolve domain names?

Accepted Answer

/etc/resolv.conf. The /etc/resolv.conf file is the standard Linux configuration file that specifies the DNS servers (nameservers) the system uses to resolve domain names into IP addresses. Since the server can ping the gateway but cannot ping the website by IP, the issue is likely name resolution, not routing. Checking /etc/resolv.conf ensures that valid DNS server entries are present and reachable. Without correct nameserver entries, the system cannot translate domain names to IPs, causing ping to fail even if the network path is fine.

Answer

/etc/network/interfaces

Answer

/etc/sysconfig/network

Answer

/etc/hosts

Question 19

You want to combine the output of 'cat file1' and 'cat file2' and count the total number of lines in the result. Which pipe sequence is correct?

Accepted Answer

wc -l file1 file2. Piping joins commands; 'cat' sends data to 'wc -l' to count lines.

Answer

cat file1 + file2 | wc -l

Answer

cat file1 file2 > wc -l

Answer

cat file1 | cat file2 | wc -l

Question 20

You are configuring a static IP address on a Debian-based server. Which file must be modified to make this change persistent across reboots?

Accepted Answer

/etc/network/interfaces. On Debian-based systems, persistent network configuration is stored in /etc/network/interfaces (or /etc/network/interfaces.d/), where you define the interface with iface eth0 inet static, address, netmask, and gateway. Editing this file and restarting networking (or rebooting) makes the static IP persist. The other files serve different purposes and do not configure interface IP addressing.

Answer

/etc/hosts

Answer

/etc/sysconfig/network-scripts/ifcfg-eth0

Answer

/etc/resolve.conf