Quick Answer
The correct answer is the VPNv4 unicast address family. In an MPLS VPN environment, this address family (AFI 128) is specifically designed to carry IPv4 VPN routes between Provider Edge (PE) routers, encapsulating both the customer’s IPv4 prefix and its route distinguisher to ensure global uniqueness. This is necessary because standard IPv4 unicast (AFI 1) only handles global Internet routes and lacks the ability to differentiate overlapping customer addresses. On the Cisco SPCOR 350-501 exam, this concept tests your understanding of how BGP extensions enable MPLS Layer 3 VPNs, often appearing in questions that contrast address families or ask which one carries VPNv4 routes. A common trap is confusing VPNv4 with IPv4 unicast or the Route Target community—remember, RT is an attribute applied to routes, not a transport address family. Memory tip: think “VPNv4 = 128” and that it’s the only AFI that carries both the route and its distinguishing label between PEs.
This 350-501 practice question tests your understanding of architecture. 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.
In an MPLS VPN environment, which address family is used to exchange VPNv4 routes between PE routers?
Route-target (RT)
Why wrong: RT is an extended community used for filtering, not an address family.
IPv4 unicast
Why wrong: IPv4 unicast does not carry VPN labels or route distinguishers.
VPNv6 unicast
Why wrong: VPNv6 is for IPv6 VPN routes.
VPNv4 unicast
VPNv4 carries both IPv4 prefixes and route distinguishers.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
VPNv4 unicast
BGP address family VPNv4 (AF 128) is used to carry IPv4 VPN routes between PEs. Option B is correct. Option A is wrong because IPv4 unicast is for global routes. Option C is wrong because VPNv6 is for IPv6. Option D is wrong because RT is a community attribute, not an address family.
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.
Route-target (RT)
Why it's wrong here
RT is an extended community used for filtering, not an address family.
IPv4 unicast
Why it's wrong here
IPv4 unicast does not carry VPN labels or route distinguishers.
VPNv6 unicast
Why it's wrong here
VPNv6 is for IPv6 VPN routes.
VPNv4 unicast
Why this is correct
VPNv4 carries both IPv4 prefixes and route distinguishers.
Related concept
Read the scenario before looking for a memorised answer.
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.
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FAQ
Architecture — This question tests Architecture — Read the scenario before looking for a memorised answer..
The correct answer is: VPNv4 unicast — BGP address family VPNv4 (AF 128) is used to carry IPv4 VPN routes between PEs. Option B is correct. Option A is wrong because IPv4 unicast is for global routes. Option C is wrong because VPNv6 is for IPv6. Option D is wrong because RT is a community attribute, not an address family.
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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