The answer is that MPLS uses label switching to forward packets. This is the defining characteristic of Multiprotocol Label Switching, where a short, fixed-length label is attached to each packet at the ingress router, and every intermediate label switch router (LSR) forwards the packet based solely on that label rather than performing a time-consuming IP routing table lookup. On the CompTIA Network+ N10-009 exam, this concept tests your understanding of how MPLS differs from traditional IP routing—a common trap is confusing MPLS with VPNs or QoS, but the core exam focus remains the label-swapping mechanism itself. Remember the memory tip: "Labels lead, IP follows"—once the label is assigned, the packet is switched through the MPLS cloud without re-examining the IP header, enabling faster forwarding and traffic engineering.
N10-009 Network Implementation Practice Question
This N10-009 practice question tests your understanding of network implementation. 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.
A network administrator is configuring a new WAN link between two offices using MPLS. Which of the following is a characteristic of MPLS?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It uses label switching to forward packets
MPLS (Multiprotocol Label Switching) operates by attaching short, fixed-length labels to packets at the ingress router. These labels are used by intermediate routers (LSRs) to make forwarding decisions based on the label rather than the IP header, which enables faster switching and traffic engineering. This label-swapping mechanism is the defining characteristic of MPLS, distinguishing it from traditional IP routing.
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.
✓
It uses label switching to forward packets
Why this is correct
MPLS routers (LSRs) assign and swap labels to route traffic efficiently, independent of IP headers.
Related concept
Read the scenario before looking for a memorised answer.
✗
It requires a dedicated point-to-point circuit
Why it's wrong here
MPLS is typically deployed over a service provider’s shared infrastructure and does not require dedicated circuits.
✗
It operates at Layer 7 of the OSI model
Why it's wrong here
MPLS operates between Layer 2 and Layer 3, sometimes called Layer 2.5.
✗
It encrypts all data in transit
Why it's wrong here
MPLS does not inherently encrypt data; encryption is handled by other protocols like IPsec.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse MPLS with a dedicated leased line or assume it provides security features like encryption, when in fact MPLS is a label-switching technology that operates below Layer 3 and above Layer 2.
Detailed technical explanation
How to think about this question
Under the hood, MPLS uses a 32-bit label header (20-bit label, 3-bit Traffic Class, 1-bit Bottom of Stack, 8-bit TTL) inserted between the Layer 2 and Layer 3 headers. Label Distribution Protocol (LDP) or RSVP-TE dynamically distributes label bindings, and Penultimate Hop Popping (PHP) is a common optimization where the last router before the egress removes the label. In real-world deployments, MPLS enables Layer 3 VPNs (RFC 4364) and traffic engineering without requiring a full mesh of circuits.
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 practitioner preparing for the N10-009 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this N10-009 question in full detail.
Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: It uses label switching to forward packets — MPLS (Multiprotocol Label Switching) operates by attaching short, fixed-length labels to packets at the ingress router. These labels are used by intermediate routers (LSRs) to make forwarding decisions based on the label rather than the IP header, which enables faster switching and traffic engineering. This label-swapping mechanism is the defining characteristic of MPLS, distinguishing it from traditional IP routing.
What should I do if I get this N10-009 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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