Quick Answer
The answer is `ss -tlnp`. This command is correct because it lists TCP listening sockets with numeric output and, crucially, includes the `-p` flag to display the process identifier (PID) and process name that owns each socket, directly revealing which process has bound port 8080. On the CompTIA Linux+ XK0-005 exam, this scenario tests your ability to troubleshoot port conflicts, a common issue when Docker containers or services fail to start. A frequent trap is reaching for the older `netstat` command, but the exam emphasizes `ss` as the modern replacement. To identify process using port Linux, always remember the `-p` flag is essential for seeing the process details; without it, you only see the port is in use, not who is using it. A simple memory tip: "ss -tlnp" can be recalled as "Show Sockets, TCP, Listen, Numbers, and Process."
This XK0-005 practice question tests your understanding of scripting, containers and automation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A Docker container using port 8080 fails to start with the error 'port is already allocated'. Which command should the administrator use to identify the process using that port?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
ss -tan
Why wrong: Shows all TCP connections, not just listening.
ss -tln
Why wrong: Shows listening ports but not the PID.
ss -tlnp
Shows listening TCP ports with PID.
ss -r
Why wrong: Shows routing table.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
ss -tlnp
Option C is correct because the `ss -tlnp` command lists TCP listening sockets (`-l`) with numeric addresses (`-n`) and shows the process identifier (PID) and process name (`-p`) that owns each socket. This directly identifies which process has bound port 8080, allowing the administrator to resolve the 'port is already allocated' error.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
ss -tan
Why it's wrong here
Shows all TCP connections, not just listening.
ss -tln
Why it's wrong here
Shows listening ports but not the PID.
ss -tlnp
Why this is correct
Shows listening TCP ports with PID.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
ss -r
Why it's wrong here
Shows routing table.
Common exam traps
The trap here is that candidates may choose `ss -tln` (option B) because it shows listening ports, but they forget the `-p` flag is required to identify the process, leading to incomplete troubleshooting.
Trap categories for this question
Command / output trap
Shows all TCP connections, not just listening.
Detailed technical explanation
The `ss` command reads socket information from the `/proc/net/tcp` and `/proc/net/tcp6` files, and the `-p` flag accesses `/proc/<pid>/fd/` to associate sockets with processes. In a Docker context, the port conflict often arises from a previously running container or a host process; using `ss -tlnp` reveals the exact PID, which can then be used with `docker ps` or `kill` to free the port. This is more efficient than `netstat` on modern systems where `ss` is the default socket statistics tool.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the XK0-005 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Scripting, Containers and Automation — study guide chapter
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FAQ
Scripting, Containers and Automation — This question tests Scripting, Containers and Automation — Read the scenario before looking for a memorised answer..
The correct answer is: ss -tlnp — Option C is correct because the `ss -tlnp` command lists TCP listening sockets (`-l`) with numeric addresses (`-n`) and shows the process identifier (PID) and process name (`-p`) that owns each socket. This directly identifies which process has bound port 8080, allowing the administrator to resolve the 'port is already allocated' error.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 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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