- A
service start
Why wrong: Service is a SysVinit command, not systemd.
- B
systemctl mask
Masks a unit, preventing it from being started.
- C
systemctl start
Starts a service unit.
- D
systemctl enable
Enables a unit to start at boot.
- E
chkconfig on
Why wrong: Chkconfig is a SysVinit tool, not systemd.
Quick Answer
The answer is systemctl enable, along with systemctl start and systemctl mask, as these are all valid systemd commands for service management. This is correct because systemd uses systemctl as its primary control interface, with subcommands like enable to configure a service to start at boot, start to launch it immediately, and mask to prevent it from being started manually or automatically. On the CompTIA Linux+ XK0-005 exam, this topic tests your ability to distinguish modern systemd tools from legacy SysVinit commands such as service and chkconfig, which are common traps. A frequent trick is that enable does not start a service immediately—it only creates the necessary symlinks for boot-time activation. To remember, think of systemctl as the Swiss Army knife for systemd: start, stop, enable, disable, mask, and unmask are all valid subcommands, while service and chkconfig are from the old init system.
XK0-005 System Management Practice Question
This XK0-005 practice question tests your understanding of system management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An administrator is managing a server using systemd and needs to control services and units. Which THREE of the following are valid systemd commands for service management? (Choose three.)
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
systemctl mask
Systemctl is the primary systemd command; start, enable, and mask are valid subcommands. Service and chkconfig are legacy SysVinit commands.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
service start
Why it's wrong here
Service is a SysVinit command, not systemd.
- ✓
systemctl mask
Why this is correct
Masks a unit, preventing it from being started.
Related concept
CIDR notation defines the prefix length.
- ✓
systemctl start
Why this is correct
Starts a service unit.
Related concept
CIDR notation defines the prefix length.
- ✓
systemctl enable
Why this is correct
Enables a unit to start at boot.
Related concept
CIDR notation defines the prefix length.
- ✗
chkconfig on
Why it's wrong here
Chkconfig is a SysVinit tool, not systemd.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Trap categories for this question
Command / output trap
Service is a SysVinit command, not systemd.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related XK0-005 subnetting questions on CIDR, address ranges, and subnet selection.
- →
System Management — study guide chapter
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System Management practice questions
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FAQ
Questions learners often ask
What does this XK0-005 question test?
System Management — This question tests System Management — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: systemctl mask — Systemctl is the primary systemd command; start, enable, and mask are valid subcommands. Service and chkconfig are legacy SysVinit commands.
What should I do if I get this XK0-005 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related XK0-005 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Last reviewed: Jun 24, 2026
This XK0-005 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the XK0-005 exam.
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