DHCP Exclusion vs Reservation for Static Assignments
Short answer
B Use a DHCP exclusion range to prevent the server from leasing the first ten IP addresses in the scope, allowing them to be assigned statically to printers.
Question
Key Takeaways
The main trap is confusing 'Exclusion' with 'Reservation'. Exclusions remove IPs from the pool entirely for auto-lease, while Reservations ensure a specific MAC gets a specific IP via DHCP. For static configuration, you must exclude the IPs from the DHCP pool.
This N10-009 question tests knowledge of DHCP scope management. The correct solution uses a DHCP exclusion range to keep specific IPs from being automatically leased, ensuring they are available for static assignment to network devices like printers.
Common mistake: Candidates often choose 'Reservation' (A) thinking it 'reserves' the IP for the printer. However, reservations still involve the DHCP server handing out the lease. To configure an IP statically (manually), you must first ensure the DHCP server won't give it away, which requires an Exclusion.
Expert Analysis
The question asks how to prevent the DHCP server from leasing specific IP addresses within an existing scope. The engineer has a scope of 100 usable addresses but wants the first ten reserved for static assignment to printers.
B. Exclusion is the correct answer. In DHCP terminology, an exclusion range defines IP addresses that are part of the scope's subnet but are explicitly marked as unavailable for automatic lease distribution. By excluding the first ten addresses, the DHCP server will skip them during dynamic allocation, leaving them free for manual configuration on the printers without causing IP conflicts.
A. Reservation is incorrect because a reservation ties a specific IP address to a client's MAC address. While this ensures a device gets the same IP, it still involves the DHCP server assigning that IP via a lease process. More importantly, reservations do not 'remove' addresses from availability in the way exclusions do; they manage assignments. If you wanted to reserve IPs for printers, you might use reservations, but the question specifically frames the need as preventing the DHCP server from using those addresses so they can be configured statically (implying no DHCP involvement). However, the most direct method to keep a block of IPs out of the auto-assignment pool is an exclusion.
C. IP helper is incorrect. This parameter is used on routers or layer 3 switches to forward DHCP broadcast requests across different subnets. It has nothing to do with managing IP address availability within a scope.
D. Option is incorrect. DHCP options provide additional configuration parameters to clients, such as the default gateway (Option 003) or DNS servers (Option 006). They do not control which IP addresses are available for lease.
As noted in community comments, defining an exclusion range prevents IP address conflicts when assigning addresses statically. This aligns with standard DHCP best practices for separating dynamic and static address pools within the same subnet.
Official Reference
https://docs.microsoft.com/en-us/windows-server/networking/technologies/dhcp/dhcp-top
This link opens the official vendor documentation in a new tab.
Exam Strategy
When answering DHCP questions, carefully distinguish between how an IP is assigned and whether DHCP is involved. If the device is configured 'statically' (manually), the DHCP server must not touch that IP, requiring an Exclusion. If the device needs a consistent IP but relies on DHCP for other settings, use a Reservation. Look for keywords like 'statically', 'manual', or 'conflict prevention' to guide your choice.
Frequently Asked Questions
What is the difference between a DHCP Reservation and an Exclusion?
Can I use a Reservation instead of an Exclusion for printers?
Community Votes
50% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.
Discussion 2 contributions
Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.
From public community threads 2
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ERB14 👍 1 Answered BDHCP Exclusion: A range of IP addresses within a DHCP scope that the DHCP server is explicitly instructed not to lease out. Defining an exclusion range for the first ten IP addresses prevents IP address conflicts when assigning those addresses statically to network equipment like printers.
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Skri113xX 👍 1 Answered DIf I had to guess, I’d pick D based on the wording of the question.
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