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300-410 Practice Question: Which TWO statements about DHCPv4 option 82 are…
Which TWO statements about DHCPv4 option 82 are true? (Choose TWO.)
⚠ Common exam trap
Cisco often tests the distinction between the command that inserts option 82 ('ip dhcp relay information option') and the command that trusts incoming option 82 ('ip dhcp relay information trusted'), leading candidates to confuse the two.
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
✓
The relay agent must be configured with the 'ip dhcp relay information option' command to insert option 82.
Option B is correct because on Cisco IOS relay agents, the 'ip dhcp relay information option' command enables the relay agent to insert the DHCPv4 option 82 (Relay Agent Information option) into client messages before forwarding them to the server. Option C is correct because the DHCP server can inspect the sub-options of option 82, such as the Circuit ID and Remote ID, and use them to select an address from a specific pool, enabling location-based address assignment. Option A is incorrect because option 82 is inserted by the relay agent, not by the DHCP client, which typically has no knowledge of the relay agent information. Option D is incorrect because option 82 is defined for DHCPv4 (RFC 3046); DHCPv6 uses a different relay mechanism with Relay-Forward/Relay-Reply messages and Interface-ID options. Option E is incorrect because 'ip dhcp relay information trusted' is used on the relay agent or a switch port to accept and forward option 82 from untrusted sources without dropping it, not to insert option 82.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Option 82 is inserted by the DHCP client to identify itself to the server.
Why it's wrong here
Option 82 is inserted by the DHCP relay agent, not the client, so this reverses the actual mechanism. It is tempting because clients do send identifying information, but that travels in the client identifier (option 61) or chaddr field, not option 82.
- ✓
The relay agent must be configured with the 'ip dhcp relay information option' command to insert option 82.
Why this is correct
Insertion of option 82 is not automatic; the relay agent must enable it with the 'ip dhcp relay information option' command. This satisfies the stem's requirement that the statement describe how the relay agent inserts the circuit ID and remote ID into forwarded DHCPv4 requests.
- ✓
The DHCP server can use option 82 to select an IP address from a specific pool based on the circuit ID.
Why this is correct
Option 82 carries the circuit ID and remote ID, letting the DHCP server match these against class or pool criteria to allocate an address from a specific scope. This satisfies the stem by describing the server-side use of option 82 for pool selection.
- ✗
Option 82 is only supported in DHCPv6.
Why it's wrong here
Option 82 exists in DHCPv4 (RFC 3046) and has no DHCPv6 equivalent, so restricting it to DHCPv6 inverts the protocol. It is tempting because DHCPv6 does carry relay-supplied options, but those use different option codes entirely.
- ✗
The 'ip dhcp relay information trusted' command must be configured on the relay agent to insert option 82.
Why it's wrong here
The 'ip dhcp relay information trusted' command controls whether the relay agent forwards option 82 received from an untrusted source; it does not govern insertion. Insertion is enabled by default on Cisco relay agents, so the command is unnecessary for that purpose.
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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.