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CCNA DHCP Question Bank (9 Questions)

Browse all 9 practice questions covering Dynamic Host Configuration Protocol for the CCNA certification exam. Each question includes the full answer and a detailed explanation to help you understand the concepts.

Question 1IP Services
Why is a DHCP relay agent (ip helper-address) needed?
ATo encrypt DHCP traffic
BDHCP Discover is a broadcast that doesn't cross routers; the relay agent forwards it as unicast to the DHCP server on a different subnet✓
CTo provide DNS services
DTo assign static IPs
Show Answer & Explanation
Correct Answer: B
Explanation:
DHCP Discover is a Layer 2 broadcast (255.255.255.255). Routers don't forward broadcasts. 'ip helper-address <DHCP-server-IP>' on the gateway interface converts the broadcast to unicast, forwarding it to the DHCP server. Also relays TFTP, DNS, NTP, TACACS.
Question 2Security Fundamentals
Which ports are classified as trusted in DHCP snooping?
AAll access ports
BPorts connected to DHCP servers and uplinks✓
CPorts connected to end-user devices
DAll trunk ports automatically
Show Answer & Explanation
Correct Answer: B
Explanation:
In DHCP snooping, trusted ports are manually configured and typically face DHCP servers or uplinks. Untrusted ports face clients and filter DHCP server messages.
Question 3Select All That ApplyIP Services
Which two features work together to prevent ARP spoofing attacks on a switch? (Choose two)
ADHCP snooping✓
BDynamic ARP Inspection✓
CPort security
DBPDU Guard
Show Answer & Explanation
Correct Answers: A, B
Explanation:
DAI uses the DHCP snooping binding table to validate ARP packets. DHCP snooping builds the IP-to-MAC binding table; DAI enforces it for ARP.
Question 4Network Access
What information is stored in the DHCP snooping binding table?
AOnly MAC addresses
BMAC address, IP address, VLAN, port, and lease time for each client that obtained an IP via DHCP on untrusted ports✓
COnly IP addresses
DOnly VLAN assignments
Show Answer & Explanation
Correct Answer: B
Explanation:
DHCP snooping binding table stores: client MAC, assigned IP, lease duration, binding type (dynamic), VLAN, and switch port. This table is used by DAI (validates ARP) and IP Source Guard (validates IP-to-MAC-to-port). 'show ip dhcp snooping binding' displays entries.
Question 5Security Fundamentals
How does DHCP snooping protect against rogue DHCP servers?
AIt encrypts DHCP traffic
BIt designates ports as trusted (toward legitimate DHCP server) or untrusted; DHCP server responses from untrusted ports are dropped✓
CIt blocks all DHCP traffic
DIt requires static IP addresses
Show Answer & Explanation
Correct Answer: B
Explanation:
DHCP snooping: trusted ports (uplinks to legitimate DHCP server) allow DHCP replies; untrusted ports (access ports) only allow DHCP requests. Rogue DHCP offers from untrusted ports are dropped. Also builds a binding table used by DAI and IP Source Guard.
Question 6IP Services
Which DHCP message is sent by the client to discover available DHCP servers?
ADHCPOFFER
BDHCPREQUEST
CDHCPDISCOVER✓
DDHCPACK
Show Answer & Explanation
Correct Answer: C
Explanation:
The DHCP process is DORA: Discover (client broadcast) → Offer (server) → Request (client) → Acknowledge (server).
Question 7IP Services
What are the four steps of the DHCP DORA process?
ADNS, OSPF, RIP, ARP
BDiscover (client broadcast), Offer (server unicast), Request (client broadcast), Acknowledge (server unicast)✓
CDownload, Open, Read, Apply
DDetect, Organize, Route, Assign
Show Answer & Explanation
Correct Answer: B
Explanation:
DHCP DORA: 1) Discover — client broadcasts to find servers, 2) Offer — server offers IP/mask/gateway/DNS/lease, 3) Request — client broadcasts acceptance of the offer, 4) Acknowledge — server confirms and commits the lease. Client broadcasts ensure all servers are notified.
Question 8IP Services
A network administrator needs to forward DHCP broadcast requests across router interfaces to reach a DHCP server on a different subnet. Which feature should be configured?
ADHCP pool on the router
BIP helper-address (DHCP relay)✓
CNAT overload
DProxy ARP
Show Answer & Explanation
Correct Answer: B
Explanation:
The 'ip helper-address' command configures a router interface to forward UDP broadcast packets (including DHCP) as unicast to a specific server IP. This is also known as DHCP relay. Without this, DHCP broadcasts would not cross router boundaries since routers do not forward broadcasts by default.
Question 9IP Services
A company's DHCP server assigns an IP address to a client. Which message sequence correctly describes the DHCP DORA process?
ADiscover → Offer → Request → Acknowledge✓
BDiscover → Request → Offer → Acknowledge
CRequest → Discover → Offer → Acknowledge
DDiscover → Offer → Acknowledge → Request
Show Answer & Explanation
Correct Answer: A
Explanation:
The DHCP process follows DORA: (1) Discover – client broadcasts to find DHCP servers, (2) Offer – server responds with an available IP, (3) Request – client requests the offered address, (4) Acknowledge – server confirms the lease. This is a fundamental networking concept tested on the CCNA.

Key DHCP Concepts for CCNA

dhcpdoradiscoverofferrequestacknowledgerelay agentdhcp snoopingip helper

CCNA DHCP Exam Tips

Dynamic Host Configuration Protocol questions in CCNA are typically scenario-based. Focus on service-level decision making aligned to official exam objectives. Priority concepts: dhcp, dora, discover, offer, request, acknowledge.

What CCNA Expects

Anchor your answer in select the most practical, secure, and scalable answer for the stated scenario.
DHCP scenarios for CCNA are frequently mapped to Domain 4 (10%), so read the objective carefully before picking controls or architecture.
Expect multi-service scenarios where DHCP interacts with IAM, networking, storage, or observability patterns rather than appearing as an isolated service question.
When two options are both technically valid, prefer the choice that best aligns with the exam's operational scope (Associate) and managed-service best practices.

High-Value DHCP Concepts

Know the core DHCP building blocks cold: dhcp, dora, discover, offer.
Review the edge-case features and limits for request, acknowledge; these details are commonly used to differentiate answer choices.
Practice service-integration reasoning: how DHCP pairs with IP Addressing, Switching, Security Fundamentals in real deployment patterns.
For CCNA, explain why the chosen DHCP design meets reliability, security, and cost expectations better than the alternatives.

Common CCNA Traps

Watch for answers that partially solve the requirement but miss operational constraints.
Questions in IP Services often include distractors that look correct for DHCP but violate least-privilege, durability, or availability requirements.
Avoid picking options purely by feature name; validate data path, failure handling, and governance impact before answering.
If the prompt hints at automation or repeatability, eliminate manual-only operational answers first.

Fast Review Checklist

Can you compare at least two DHCP implementation paths and justify which one best fits the scenario?
Can you map the chosen answer back to IP Services (10%) outcomes for CCNA?
Can you explain security and access boundaries for DHCP without relying on default-open assumptions?
Can you describe how DHCP integrates with IP Addressing and Switching during failure, scaling, and monitoring events?

Exam Domains Covering DHCP

Domain 4IP Services10%

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