Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A company's public web server is experiencing a flood of TCP SYN packets from multiple external IP addresses. The server's connection table is full, causing new legitimate connections to be dropped. Which of the following mitigation techniques should be implemented to protect the server while still allowing legitimate traffic?
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
Implement SYN cookies on the server.
SYN cookies encode connection information in the SYN-ACK response, enabling the server to remain stateless until the handshake completes. This prevents the connection table from filling up.
B
Distractor review
Increase the server's TCP connection backlog.
Increasing the backlog provides more room for incomplete connections, but the server's resources are still finite. It is not a long-term mitigation for a large SYN flood.
C
Distractor review
Enable bogon filtering on the perimeter firewall.
Bogon filtering blocks traffic from private or unallocated IP addresses. Attackers often use spoofed addresses, but this does not address the connection table exhaustion from a high volume of SYN packets.
D
Distractor review
Deploy an intrusion prevention system (IPS) with signature detection.
An IPS can detect and block SYN floods, but it may not be as performant as server-side SYN cookies for handling high-rate attacks. SYN cookies are a more direct and often recommended mitigation.
Common exam trap
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Technical deep dive
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
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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?
Static NAT maps one inside address to one outside address.
What is the correct answer to this question?
The correct answer is: Implement SYN cookies on the server. — A SYN flood attack consumes server resources by sending many SYN packets without completing the three-way handshake. SYN cookies allow the server to handle incoming SYN packets without allocating memory to the connection table until the handshake is completed. This technique is lightweight and effective. Increasing TCP backlog (A) might temporarily help but does not prevent resource exhaustion. Bogon filtering (B) blocks traffic from invalid IPs, not specifically SYN floods. An IPS (D) may detect the flood but might not handle the sheer volume as efficiently as SYN cookies.
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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