350-501 Architecture Practice Question
A service provider is deploying Segment Routing Traffic Engineering (SR-TE) with a Path Computation Element (PCE). The PCE fails to compute a path for an SR-TE policy configured with constraint 'avoid nodes in affinity red'. The core network has red affinity assigned to several nodes. Which is the most likely cause?
⚠ Common exam trap
Cisco often tests the misconception that a path computation failure is due to misconfigured affinities on the network devices, when in fact the root cause is the PCE lacking the updated link-state database with those affinity attributes.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The PCE does not have the updated link-state database with the affinity attributes
The PCE computes paths based on the link-state database (LSDB) it receives from the IGP (e.g., OSPF or IS-IS). If the LSDB does not include the affinity (color) attributes for the nodes, the PCE cannot evaluate the 'avoid nodes in affinity red' constraint. This results in a path computation failure, even though the affinities are correctly configured on the network devices.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The PCE does not have the updated link-state database with the affinity attributes
Why this is correct
PCE needs current IGP database to honor constraints; if not updated, it cannot compute paths with avoid conditions.
- ✗
The headend router does not have the SR-TE policy configured with the correct path
Why it's wrong here
The policy is configured; the issue is path computation, not policy configuration.
- ✗
The PCE is not reachable from the headend router
Why it's wrong here
If unreachable, no path could be computed at all; the scenario describes a specific failure with red affinity.
- ✗
The SR-TE policy is configured with a strict explicit path that conflicts with the constraint
Why it's wrong here
Explicit path would override constraint; but the policy likely uses dynamic path computation.
- ✗
The red affinity is not properly configured in the network
Why it's wrong here
The affinities are assigned, but PCE may not have them in its database.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.