350-501 Networking Practice Question
In an IS-IS network, a service provider wants to achieve fast convergence using Partial Route Computation (PRC). Which of the following events triggers a PRC instead of a full SPF?
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
✓
An IP prefix is withdrawn from a directly connected network
PRC is triggered when an IP prefix changes (addition, removal, or metric change) without a change in the IS-IS topology (i.e., no change in adjacency or reachable IS-IS neighbors). PRC only recalculates the affected prefixes, avoiding full SPF.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A router's system ID changes
Why it's wrong here
System ID change affects the router's identity and triggers full SPF.
- ✗
An LSP with a new fragment arrives
Why it's wrong here
New LSP fragments often indicate topology change, triggering full SPF.
- ✗
A new adjacency is formed between two routers
Why it's wrong here
Topology change triggers full SPF, not PRC.
- ✓
An IP prefix is withdrawn from a directly connected network
Why this is correct
Correct. A prefix change without topology change triggers PRC.
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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.