The answer is that the managed-config-flag (M flag) in Router Advertisement messages directs hosts to use stateful DHCPv6 for both IPv6 address assignment and other configuration parameters like DNS servers. This flag, defined in RFC 3315 and RFC 4861, overrides stateless address autoconfiguration (SLAAC) when set to 1, forcing hosts to obtain a full IPv6 address and additional settings from a DHCPv6 server rather than generating an address from the advertised prefix. On the Cisco CCNP ENARSI 300-410 exam, this concept tests your understanding of how Router Advertisements control host behavior in an IPv6 network; a common trap is confusing the M flag with the O (other-config) flag, which only requests additional parameters while allowing SLAAC for addressing. Remember the mnemonic: M for "Must get an address" from DHCPv6, while O is for "Other stuff only."
300-410 DHCP (IPv4 and IPv6) Practice Question
This 300-410 practice question tests your understanding of dhcp (ipv4 and ipv6). This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 DHCPv6, what is the purpose of the 'managed-config-flag' in Router Advertisement messages?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It indicates that hosts should use DHCPv6 to obtain their IPv6 address and other configuration parameters.
The 'managed-config-flag' (M flag) in Router Advertisement (RA) messages, as defined in RFC 3315 and RFC 4861, tells hosts to use stateful DHCPv6 for both IPv6 address assignment and other configuration parameters (e.g., DNS servers). When set to 1, hosts must use DHCPv6 to obtain their IPv6 address, overriding SLAAC for addressing. This flag is part of the RA's prefix information option and directly controls whether hosts perform stateful or stateless address configuration.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
It indicates that hosts should use DHCPv6 to obtain their IPv6 address and other configuration parameters.
Why this is correct
The M flag signals stateful DHCPv6, where hosts get both addresses and other info from a DHCPv6 server.
Related concept
Read the scenario before looking for a memorised answer.
✗
It indicates that hosts should use SLAAC for addressing and DHCPv6 for other configuration only.
Why it's wrong here
That is the purpose of the other-config-flag (O flag), not the managed-config-flag.
✗
It indicates that the router is a DHCPv6 server.
Why it's wrong here
The flag is used in Router Advertisements to inform hosts, not to advertise the router as a server.
✗
It indicates that hosts should use only stateless address autoconfiguration.
Why it's wrong here
The M flag tells hosts to use DHCPv6, not SLAAC alone.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between the M flag and the O flag, and the trap here is confusing the 'managed-config-flag' (for addressing + other config) with the 'other-config-flag' (for other config only), leading candidates to incorrectly select option B.
Detailed technical explanation
How to think about this question
The M flag is a single bit in the RA's 'Flags' field (bit 6), and its setting is independent of the O flag (bit 7). In practice, an enterprise might set the M flag to 1 to enforce centralized address management via DHCPv6, ensuring all hosts receive addresses from a controlled pool, which is critical for auditing and security. A common subtlety is that when the M flag is 1, hosts must still process the O flag; if both are 1, DHCPv6 provides both addresses and other config, but if M=1 and O=0, DHCPv6 provides only addresses (other config must be obtained via other means, which is rare).
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 300-410 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
DHCP (IPv4 and IPv6) — This question tests DHCP (IPv4 and IPv6) — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: It indicates that hosts should use DHCPv6 to obtain their IPv6 address and other configuration parameters. — The 'managed-config-flag' (M flag) in Router Advertisement (RA) messages, as defined in RFC 3315 and RFC 4861, tells hosts to use stateful DHCPv6 for both IPv6 address assignment and other configuration parameters (e.g., DNS servers). When set to 1, hosts must use DHCPv6 to obtain their IPv6 address, overriding SLAAC for addressing. This flag is part of the RA's prefix information option and directly controls whether hosts perform stateful or stateless address configuration.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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