350-501 Networking Practice Question
A service provider is deploying segment routing in their MPLS core. They want to use an IGP as the control plane for label distribution without running LDP or RSVP-TE. Which IGP is best suited for this purpose?
⚠ Common exam trap
Test-takers frequently think OSPF is also a valid choice, but the question specifically asks for the IGP best suited for segment routing without LDP or RSVP-TE, and while OSPF does support SR (RFC 8665), IS-IS is historically more common in service provider cores due to its native support for CLNS and easier migration from LDP to SR.
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
✓
IS-IS
IS-IS is the best-suited IGP for segment routing in an MPLS core because it natively supports the Segment Routing (SR) extensions defined in RFC 8667. These extensions allow IS-IS to advertise Prefix-SIDs and Adjacency-SIDs directly within the link-state database, enabling label distribution without requiring LDP or RSVP-TE. This makes IS-IS a natural fit for service providers deploying SR-MPLS.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
BGP
Why it's wrong here
BGP is an EGP, not an IGP, and requires additional components.
- ✗
EIGRP
Why it's wrong here
EIGRP does not support segment routing.
- ✓
IS-IS
Why this is correct
IS-IS supports segment routing extensions and is widely used in SP cores.
- ✗
RIP
Why it's wrong here
RIP is outdated and does not support segment routing.
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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.