Question 790 of 2,152

DHCP (IPv4 and IPv6) →hardMultiple ChoiceObjective-mapped

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.

An engineer configures DHCPv6 prefix delegation on a router with multiple requesting interfaces. The router receives a /48 prefix from the server, but only one interface gets a /64 sub-prefix. Which is the most likely explanation?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

A
Only one interface is configured with 'ipv6 address prefix-name ::1:0:0:0:1/64' using the delegated prefix; other interfaces lack this configuration.
Correct: The delegated prefix must be explicitly used on each interface with the appropriate 'ipv6 address' command referencing the prefix name.
B
The DHCPv6 server only delegates a single /64 prefix, not a /48.
Why wrong: Incorrect: The question states a /48 is received.
C
The router's 'ipv6 dhcp client pd' command is missing the 'rapid-commit' option.
Why wrong: Incorrect: Rapid commit speeds up the process but does not affect the number of interfaces.
D
The router has 'ipv6 dhcp client information refresh' set to a high value, delaying updates.
Why wrong: Incorrect: This affects lease renewal, not the initial assignment.

Full breakdown with real-world context →

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

✓

Only one interface is configured with 'ipv6 address prefix-name ::1:0:0:0:1/64' using the delegated prefix; other interfaces lack this configuration.

Option A is correct because the router receives a /48 prefix from the DHCPv6 server, but each requesting interface must explicitly reference the delegated prefix using the 'ipv6 address prefix-name' command to derive a /64 sub-prefix. If only one interface has this configuration, only that interface will obtain a /64 sub-prefix; the other interfaces lack the necessary command to consume the delegated prefix.

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.

✓
Only one interface is configured with 'ipv6 address prefix-name ::1:0:0:0:1/64' using the delegated prefix; other interfaces lack this configuration.
Why this is correct
Correct: The delegated prefix must be explicitly used on each interface with the appropriate 'ipv6 address' command referencing the prefix name.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The DHCPv6 server only delegates a single /64 prefix, not a /48.
Why it's wrong here
Incorrect: The question states a /48 is received.
✗
The router's 'ipv6 dhcp client pd' command is missing the 'rapid-commit' option.
Why it's wrong here
Incorrect: Rapid commit speeds up the process but does not affect the number of interfaces.
✗
The router has 'ipv6 dhcp client information refresh' set to a high value, delaying updates.
Why it's wrong here
Incorrect: This affects lease renewal, not the initial assignment.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between receiving a delegated prefix and actually assigning sub-prefixes to interfaces, trapping candidates who assume that receiving a /48 automatically gives every interface a /64.

Detailed technical explanation

How to think about this question

DHCPv6 prefix delegation (RFC 3633) allows a client to request a larger prefix (e.g., /48) and then sub-delegate /64 prefixes to downstream interfaces. The 'ipv6 address prefix-name' command uses the delegated prefix name (from 'ipv6 dhcp client pd') to construct a specific /64 address; without this command on an interface, the interface does not automatically receive any sub-prefix. In real-world deployments, forgetting to apply this command on all downstream interfaces is a common misconfiguration that leads to partial IPv6 connectivity.

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.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this 300-410 question test?

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: Only one interface is configured with 'ipv6 address prefix-name ::1:0:0:0:1/64' using the delegated prefix; other interfaces lack this configuration. — Option A is correct because the router receives a /48 prefix from the DHCPv6 server, but each requesting interface must explicitly reference the delegated prefix using the 'ipv6 address prefix-name' command to derive a /64 sub-prefix. If only one interface has this configuration, only that interface will obtain a /64 sub-prefix; the other interfaces lack the necessary command to consume the delegated prefix.

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.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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