Quick Answer
The answer is the Map-Server (MS). This LISP component is responsible for maintaining the authoritative EID-to-RLOC mapping database and for responding to Map-Request messages from Ingress Tunnel Routers (ITRs). When an ITR needs to find the RLOC for a destination EID, it sends a Map-Request to the Map-Resolver (MR), which forwards it to the MS; the MS then replies with the correct mapping, enabling the ITR to encapsulate and forward traffic. On the Cisco SPCOR 350-501 exam, this question tests your understanding of LISP control-plane roles, often appearing in a scenario about service provider mobility or multihoming. A common trap is confusing the Map-Server with the Map-Resolver—remember that the MR forwards requests, while the MS holds the database and provides the answer. A simple memory tip: the Map-Server is the “source of truth” for mappings, just like a DNS server holds the IP for a domain name.
This 350-501 practice question tests your understanding of services. 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 service provider is deploying LISP (Locator/ID Separation Protocol) to provide mobility and multihoming for customer endpoints. Which LISP component is responsible for maintaining the mapping between Endpoint Identifiers (EIDs) and Routing Locators (RLOCs) and for responding to Map-Request messages from ITRs?
Ingress Tunnel Router (ITR)
Why wrong: ITR encapsulates packets and sends Map-Requests, but does not maintain the mapping.
Map-Server (MS)
MS maintains the EID-to-RLOC mapping and responds to Map-Requests.
Map-Resolver (MR)
Why wrong: MR forwards Map-Requests to the MS; it does not hold mappings.
Egress Tunnel Router (ETR)
Why wrong: ETR decapsulates packets and registers EID prefixes with the MS.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Map-Server (MS)
Option B is correct. The Map-Server maintains the EID-to-RLOC mapping database and responds to Map-Requests. Option A (ITR) encapsulates and sends packets to the ETR. Option C (ETR) decapsulates and receives packets. Option D (MR) forwards Map-Requests to the MS, but the MS provides the mapping.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Ingress Tunnel Router (ITR)
Why it's wrong here
ITR encapsulates packets and sends Map-Requests, but does not maintain the mapping.
Map-Server (MS)
Why this is correct
MS maintains the EID-to-RLOC mapping and responds to Map-Requests.
Related concept
Read the scenario before looking for a memorised answer.
Map-Resolver (MR)
Why it's wrong here
MR forwards Map-Requests to the MS; it does not hold mappings.
Egress Tunnel Router (ETR)
Why it's wrong here
ETR decapsulates packets and registers EID prefixes with the MS.
Common exam traps
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the 350-501 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.
What to study next
Identify which 350-501 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Services — study guide chapter
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Services practice questions
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All 350-501 questions
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Cisco SPCOR / CCNP Service Provider Core 350-501 study guide
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350-501 practice test guide
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FAQ
Services — This question tests Services — Read the scenario before looking for a memorised answer..
The correct answer is: Map-Server (MS) — Option B is correct. The Map-Server maintains the EID-to-RLOC mapping database and responds to Map-Requests. Option A (ITR) encapsulates and sends packets to the ETR. Option C (ETR) decapsulates and receives packets. Option D (MR) forwards Map-Requests to the MS, but the MS provides the mapping.
Identify which 350-501 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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