The answer is to use `apply-path` with a regular expression inside a configuration group. This approach is correct because `apply-path` dynamically generates configuration stanzas by matching interface names against a pattern, such as `ge-*`, allowing Junos to automatically apply the same BGP settings to all interfaces starting with 'ge-' without manual enumeration. On the JNCIA-Junos exam, this tests your understanding of configuration groups and automation, often appearing as a scenario where you must avoid static interface lists. A common trap is confusing `apply-path` with `apply-groups` or trying to use wildcards directly in interface statements, which Junos does not support. Remember the key distinction: `apply-groups` applies a block of configuration, while `apply-path` dynamically generates configuration based on a pattern match. A useful memory tip is to think of `apply-path` as a "smart for-loop" for your configuration—it iterates over matching objects and applies the template automatically.
JNCIA-JUNOS Junos Configuration Basics Practice Question
This JNCIA-JUNOS practice question tests your understanding of junos configuration basics. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 wants to apply the same BGP configuration to all interfaces whose names start with 'ge-'. Which approach would dynamically match these interfaces?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use apply-path referencing a regular expression in the configuration group
Option C is correct because the `apply-path` statement in a configuration group can dynamically match interfaces based on a regular expression pattern. By using `apply-path` with a regular expression like `ge-*` inside the configuration group, Junos will automatically apply the BGP configuration to all interfaces whose names match that pattern without manual enumeration.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Define a configuration group and use apply-groups with [edit interfaces ge-*]
Why it's wrong here
apply-groups does not support wildcard patterns; it applies the entire group.
✗
Create a firewall filter that matches ge- interfaces
Use apply-path referencing a regular expression in the configuration group
Why this is correct
apply-path dynamically matches interfaces based on a path pattern.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use an interface-range named 'ge-interfaces' listing all ge- interfaces
Why it's wrong here
Static list, does not dynamically match new interfaces.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `apply-groups` with `apply-path`, assuming that `apply-groups` supports wildcards or regex in the target path, when in fact only `apply-path` provides dynamic pattern matching for interface names.
Detailed technical explanation
How to think about this question
The `apply-path` statement allows referencing a regular expression within a configuration group to match interface names dynamically, which is part of Junos automation capabilities. Under the hood, Junos evaluates the regex against the existing interface names at commit time and applies the configuration block to all matching interfaces. This is particularly useful in large-scale deployments where interface naming conventions are consistent, such as in data center leaf-spine architectures with hundreds of ge- interfaces.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Junos Configuration Basics — This question tests Junos Configuration Basics — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use apply-path referencing a regular expression in the configuration group — Option C is correct because the `apply-path` statement in a configuration group can dynamically match interfaces based on a regular expression pattern. By using `apply-path` with a regular expression like `ge-*` inside the configuration group, Junos will automatically apply the BGP configuration to all interfaces whose names match that pattern without manual enumeration.
What should I do if I get this JNCIA-JUNOS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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