The answer is `systemctl mask` and `systemctl disable`. While both commands prevent a service from starting, they operate at different levels: `disable` removes the symlinks that trigger automatic startup at boot, but the service can still be started manually with `systemctl start`; `mask` goes further by linking the service to `/dev/null`, making it impossible to start either automatically or manually. On the CompTIA Linux+ XK0-005 exam, this distinction is a frequent trap—candidates often confuse `disable` with a full block, or forget that `stop` only halts the current session. The exam tests your understanding of systemd’s unit state management, so remember that `disable` prevents autostart, while `mask` prevents any start. A simple memory tip: think of `disable` as “don’t launch at boot” and `mask` as “completely hidden and unreachable.”
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.
Which TWO commands effectively disable a systemd service to prevent it from starting, either automatically or manually? (Select 2.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
systemctl disable
Options B (systemctl disable) and C (systemctl mask) are correct. Disable prevents automatic startup, mask prevents any startup. Stop only halts current session, kill sends signals, reset-failed resets failure state.
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.
✓
systemctl disable
Why this is correct
Disable removes the symlink that enables the service at boot, preventing automatic start.
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.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
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 — This question tests System Management — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: systemctl disable — Options B (systemctl disable) and C (systemctl mask) are correct. Disable prevents automatic startup, mask prevents any startup. Stop only halts current session, kill sends signals, reset-failed resets failure state.
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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Question Discussion
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