The answer is source-based path selection, Segment Routing Global Block (SRGB), and Topology-Independent Loop-Free Alternate (TI-LFA). These three features are unique to Segment Routing because traditional MPLS with LDP relies on hop-by-hop label distribution and cannot enforce a source-routed path, lacks a network-wide coordinated label range like the SRGB, and has no built-in mechanism for fast reroute that is both topology-independent and loop-free. On the Cisco SPCOR 350-501 exam, this question tests your ability to distinguish SR’s inherent capabilities from legacy MPLS control planes; a common trap is confusing stateful TE tunnels from RSVP-TE or PCE, which are optional in SR but not unique to it. To remember, think of the acronym “SST” for Source routing, SRGB, and TI-LFA — all three are native to SR and absent in LDP-based MPLS.
350-501 MPLS and Segment Routing Practice Question
This 350-501 practice question tests your understanding of mpls and segment routing. 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 three features are unique to Segment Routing when compared to traditional MPLS with LDP? (Choose three)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Source-based path selection
Source-based path selection, SRGB, and TI-LFA are inherent to SR and not present in LDP-based MPLS. Stateful TE tunnels exist in RSVP-TE, and PCE is optional for SR.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Source-based path selection
Why this is correct
SR uses source routing where the path is encoded in the packet header.
Related concept
Static NAT maps one inside address to one outside address.
✓
TI-LFA fast convergence
Why this is correct
TI-LFA is a fast-reroute mechanism specific to Segment Routing.
Related concept
Static NAT maps one inside address to one outside address.
✗
Stateful TE tunnels
Why it's wrong here
Stateful TE tunnels are also possible with RSVP-TE.
✓
Network-wide label range (SRGB)
Why this is correct
SRGB is a reserved label block used uniformly across the domain.
Related concept
Static NAT maps one inside address to one outside address.
✗
Centralized controller (PCE) requirement
Why it's wrong here
PCE is not required for SR; it can operate without a controller.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-501 NAT questions on configuration and troubleshooting.
MPLS and Segment Routing — This question tests MPLS and Segment Routing — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Source-based path selection — Source-based path selection, SRGB, and TI-LFA are inherent to SR and not present in LDP-based MPLS. Stateful TE tunnels exist in RSVP-TE, and PCE is optional for SR.
What should I do if I get this 350-501 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 350-501 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 350-501 practice question is part of Courseiva's free Cisco 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 350-501 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.