Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A security analyst observes that a workstation on the network is sending unsolicited ARP replies stating that the workstation's MAC address corresponds to the default gateway IP for all subnets. This behavior is causing other devices to send traffic destined for external networks to the workstation instead of the legitimate gateway. Which type of attack is being performed?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
A: ARP spoofing
ARP spoofing involves sending fake ARP messages to associate the attacker's MAC with another IP, typically the gateway.
B
Distractor review
B: DHCP starvation
DHCP starvation floods the DHCP server with requests to exhaust the IP pool, preventing legitimate clients from obtaining addresses, but does not involve ARP.
C
Distractor review
C: DNS poisoning
DNS poisoning corrupts DNS cache entries to redirect domain names to incorrect IPs, which operates at a higher layer.
D
Distractor review
D: MAC flooding
MAC flooding sends many frames with different MAC addresses to fill the switch's CAM table, causing it to flood traffic, but it doesn't involve ARP replies claiming the gateway.
Common exam trap
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Technical deep dive
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A network engineer needs to connect two switches located 400 meters apart. The cable run includes high electromagnetic interference from nearby machinery. The engineer decides to use fiber optic cabling. Which transceiver type and fiber combination should be used to ensure the link reaches 400 meters while remaining cost-effective?
Question 2
A network engineer is designing a new switched network and needs to ensure that broadcast traffic from one department does not reach another department's workstations. The engineer plans to use VLANs. Which of the following must be configured on the switches to isolate broadcast domains as intended?
Question 3
A security engineer is configuring a site-to-site VPN between two branch offices. The requirement is to encrypt all traffic between the two networks using IPsec. Which IPsec mode should be used to encrypt the entire IP packet including the original header?
Question 4
A network administrator is connecting two switches to increase bandwidth and provide redundancy. Which technology should be used to combine multiple physical links into a single logical link?
Question 5
A network administrator is experiencing issues where unauthorized devices are offering IP addresses to clients, causing connectivity problems. Which security feature should be enabled on switches to prevent this?
Question 6
A network administrator is troubleshooting a connectivity issue and suspects the problem is related to the physical cabling. At which layer of the OSI model should the administrator begin their investigation?
FAQ
Questions learners often ask
What does this N10-009 question test?
CIDR notation defines the prefix length.
What is the correct answer to this question?
The correct answer is: A: ARP spoofing — This is ARP spoofing (or ARP poisoning). The attacker sends forged ARP replies to associate their MAC address with the IP address of the default gateway, causing traffic to be misdirected. This allows the attacker to intercept or modify traffic. Defenses include dynamic ARP inspection (DAI).
What should I do if I get this N10-009 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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