Question 1,051 of 1,389
CCNA Network Services and Security Practice Question
Exhibit
R1# show ip dhcp conflict IP address Detection method Detection time VRF 192.168.1.50 Ping Mar 01 2025 10:23 AM 192.168.1.51 Ping Mar 01 2025 10:24 AM 192.168.1.52 Ping Mar 01 2025 10:25 AM 192.168.1.53 Ping Mar 01 2025 10:26 AM 192.168.1.54 Ping Mar 01 2025 10:27 AM 192.168.1.55 Ping Mar 01 2025 10:28 AM 192.168.1.56 Ping Mar 01 2025 10:29 AM 192.168.1.57 Ping Mar 01 2025 10:30 AM 192.168.1.58 Ping Mar 01 2025 10:31 AM 192.168.1.59 Ping Mar 01 2025 10:32 AM
Refer to the exhibit. A network engineer is troubleshooting DHCP issues on a branch office network. Several users report that new devices are unable to obtain IP addresses, even though the DHCP pool configured on R1 appears to have sufficient free addresses. The engineer executes the show ip dhcp conflict command and observes the output. Based on the output, what is the most likely cause of the problem?
⚠ Common exam trap
Cisco often tests the distinction between a DHCP exclusion range (which prevents addresses from being offered) and a DHCP conflict (which occurs after an address is offered but found to be in use), tempting candidates to confuse the two concepts.
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
✓
Several hosts on the network are using static IP addresses from the DHCP pool range, causing the DHCP server to mark those addresses as conflicts and depleting the available pool.
The output of 'show ip dhcp conflict' lists IP addresses that the DHCP server detected as already in use via ping or gratuitous ARP. When hosts use static IP addresses from the DHCP pool range, the server marks those addresses as conflicts and removes them from the available pool, effectively depleting the pool even though the scope shows free addresses. This matches the scenario where new devices cannot obtain IP addresses despite the pool appearing to have sufficient free addresses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The DHCP scope is misconfigured with an exclusion range that includes 192.168.1.50 to 192.168.1.59.
Why it's wrong here
The DHCP exclusion range is a deliberate administrative setting that tells the server never to lease those addresses; excluded addresses are not probed with ping and never appear in `show ip dhcp conflict`. `show ip dhcp conflict` lists only addresses where the server performed an active duplicate-address check and received a response, proving something was already using that IP. An exclusion range would shrink the pool but would not generate Ping conflict entries, so it cannot explain the exhibit.
- ✗
The ping timeout on the DHCP server is set too low, causing it to falsely detect conflicts.
Why it's wrong here
A shorter ping timeout would make the DHCP server abort its reachability check sooner, so it would be more likely to miss a reply and treat the address as free, not declare a conflict. The conflict entries shown with detection method 'Ping' mean the server actually received ICMP echo replies from those addresses, confirming they are in use by other hosts. Therefore the timeout being too low would reduce conflicts, not create false ones, and the exhibit demonstrates genuine occupancy.
- ✓
Several hosts on the network are using static IP addresses from the DHCP pool range, causing the DHCP server to mark those addresses as conflicts and depleting the available pool.
Why this is correct
Each conflict entry with detection method 'Ping' indicates the server attempted to verify the address and received a reply, meaning a device is already using that IP statically or from another source. The server then marks it as a conflict and withdraws it from the pool, shrinking the pool until no addresses remain free.
- ✗
The DHCP server is not properly releasing expired leases, causing the conflict table to fill up.
Why it's wrong here
Conflicts are not caused by lease expiration. They are generated only when the server detects a duplicate address during the pre‑assignment check. Expired leases simply return to the pool; they do not populate the conflict table.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓Several hosts on the network are using static IP addresses from the DHCP pool range, causing the DHCP server to mark those addresses as conflicts and depleting the available pool.Correct answer▾
Why this is correct
Each conflict entry with detection method 'Ping' indicates the server attempted to verify the address and received a reply, meaning a device is already using that IP statically or from another source. The server then marks it as a conflict and withdraws it from the pool, shrinking the pool until no addresses remain free.
✗The DHCP scope is misconfigured with an exclusion range that includes 192.168.1.50 to 192.168.1.59.Wrong answer — click to see why▾
Why this is wrong here
Candidates may confuse administratively excluded addresses with dynamically detected conflicts.
✗The ping timeout on the DHCP server is set too low, causing it to falsely detect conflicts.Wrong answer — click to see why▾
Why this is wrong here
The misconception is that aggressive ping settings create false conflicts, when in fact a conflict entry proves a reply was received.
✗The DHCP server is not properly releasing expired leases, causing the conflict table to fill up.Wrong answer — click to see why▾
Why this is wrong here
Candidates might think that conflicts represent stale entries, but a conflict is a permanent record of a detected collision, not a lease state.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
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Last reviewed: Jul 4, 2026
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