easyMultiple Choice
300-410 Practice Question: Which DHCPv6 option carries the DNS recursive…
Which DHCPv6 option carries the DNS recursive name server information?
⚠ Common exam trap
Cisco often tests the distinction between DHCPv4 Option 6 and DHCPv6 Option 23, trapping candidates who assume the same option number applies to both protocols.
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
✓
Option 23 (DNS Recursive Name Server)
DHCPv6 Option 23 (DNS Recursive Name Server) is specifically defined in RFC 3646 to carry the IPv6 addresses of DNS recursive name servers to DHCPv6 clients. This is the standard mechanism for IPv6 hosts to learn DNS server addresses via DHCPv6, analogous to DHCPv4 Option 6 for IPv4.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Option 6 (Domain Name Server)
Why it's wrong here
DHCPv6 uses Option 23 (DNS Recursive Name Server) to carry resolver addresses; Option 6 is the DHCPv4 Domain Name Server option and does not exist in DHCPv6. It is tempting because the numbering matches the familiar IPv4 equivalent, but the v6 option space was renumbered entirely.
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Option 23 (DNS Recursive Name Server)
Why this is correct
DHCPv6 Option 23 carries the DNS recursive name server information, satisfying the stem's requirement for the option that supplies resolver addresses to IPv6 clients. It lists one or more IPv6 addresses of recursive DNS servers, distinct from Option 24, which provides the domain search list rather than resolver addresses.
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Option 24 (Domain Search List)
Why it's wrong here
Option 24 supplies the domain search list, a set of suffixes appended during name resolution, not the recursive name server addresses themselves. It is tempting because both concern DNS configuration, and it would be correct if the question asked which option provides the suffix list used for unqualified hostname queries.
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Option 21 (SIP Server Domain Name)
Why it's wrong here
Option 21 carries SIP server domain names for VoIP endpoint configuration, which is unrelated to DNS recursive name server information. It is tempting because it is a genuine DHCPv6 option conveying server names, and it would be correct if the question asked how SIP proxy or registrar domains are delivered to clients.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 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 300-410 exam.