Quick Answer
The answer is the command show interfaces ge-0/0/0 detail. This is the correct choice because the no-ttl-propagate setting is applied at the interface level to prevent TTL decrement for protocols like MPLS, and only the detail view of the interface displays all operational properties, including TTL propagation settings that may be hidden in a configuration-only output. On the JNCIA-Junos exam, this question tests your understanding of how Junos separates configuration from operational state, and a common trap is assuming show configuration interfaces will reveal the setting when it may not show defaults. To verify no-ttl-propagate on an interface, you must always use the detail keyword to see the effective behavior. Memory tip: think "detail reveals the TTL deal."
This JNCIA-JUNOS practice question tests your understanding of junos configuration basics. 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.
While troubleshooting a routing loop, an administrator captures traffic on an interface and sees packets with TTL=1 being forwarded. This indicates a potential misconfiguration. Which command can be used to verify whether the interface is configured with 'no-ttl-propagate'?
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.
show interfaces ge-0/0/0 detail
Displays TTL propagate flags under the interface details.
show configuration interfaces ge-0/0/0
Why wrong: Shows configuration but may not show TTL propagate if not set explicitly.
monitor traffic interface ge-0/0/0
Why wrong: Captures packets but does not show configuration.
show route forwarding-table
Why wrong: Does not show per-interface TTL settings.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
show interfaces ge-0/0/0 detail
The 'no-ttl-propagate' configuration is applied at the interface level to prevent TTL decrement for certain protocols like MPLS. To verify this setting, you must check the interface configuration details, which are displayed by 'show interfaces ge-0/0/0 detail'. This command shows all interface properties, including any TTL propagation settings, whereas the configuration-only view may omit operational defaults.
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.
show interfaces ge-0/0/0 detail
Why this is correct
Displays TTL propagate flags under the interface details.
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.
show configuration interfaces ge-0/0/0
Why it's wrong here
Shows configuration but may not show TTL propagate if not set explicitly.
monitor traffic interface ge-0/0/0
Why it's wrong here
Captures packets but does not show configuration.
show route forwarding-table
Why it's wrong here
Does not show per-interface TTL settings.
Common exam traps
The trap here is that candidates often assume 'show configuration interfaces' will reveal all active settings, but Junos hides default or inherited parameters unless explicitly configured, making 'show interfaces detail' necessary to see operational TTL propagation behavior.
Trap categories for this question
Command / output trap
Shows configuration but may not show TTL propagate if not set explicitly.
Detailed technical explanation
In Junos, TTL propagation is controlled by the 'no-ttl-propagate' statement under the interface configuration hierarchy, which affects how TTL is handled for MPLS and other tunneled traffic. When enabled, the router does not decrement the TTL of incoming packets before forwarding, which can cause loops if misapplied. The 'show interfaces detail' output includes the 'TTL propagate' status, allowing administrators to confirm whether the interface is set to propagate or not propagate TTL.
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 JNCIA-JUNOS 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.
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FAQ
Junos Configuration Basics — This question tests Junos Configuration Basics — Read the scenario before looking for a memorised answer..
The correct answer is: show interfaces ge-0/0/0 detail — The 'no-ttl-propagate' configuration is applied at the interface level to prevent TTL decrement for certain protocols like MPLS. To verify this setting, you must check the interface configuration details, which are displayed by 'show interfaces ge-0/0/0 detail'. This command shows all interface properties, including any TTL propagation settings, whereas the configuration-only view may omit operational defaults.
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 24, 2026
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