Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A network technician is troubleshooting an issue where users on VLAN 20 can access internal servers and the default gateway but cannot reach any external websites. The router's ACL is configured to permit all outbound traffic. What is the most likely cause of this issue?
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
Distractor review
The DNS server is unreachable from the VLAN
DNS issues would affect name resolution, but the users can access internal resources by IP. Additionally, the problem is specifically with external websites, and if DNS were the root cause, they would likely be unable to resolve any hostnames, not just external ones.
B
Distractor review
The DHCP server is not providing a default gateway
A missing default gateway would prevent access to any network beyond the local subnet, including internal servers. Since internal servers are accessible, the default gateway is correctly configured.
C
Best answer
NAT is not configured or is misconfigured on the router
NAT is required to translate private VLAN IPs to a public IP for internet access. Even if ACLs permit traffic, without proper NAT, packets will not be forwarded to the internet. This matches the symptom of being able to reach internal resources but not external ones.
D
Distractor review
The switch port for the router is in the wrong VLAN
If the switch port were in the wrong VLAN, the router would not be reachable, but users can ping the default gateway. This indicates Layer 2 connectivity is correct.
Common exam trap
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Technical deep dive
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
- Access ports place end devices into a single VLAN.
- Trunk ports carry multiple VLANs between switches.
- Allowed VLAN lists decide which VLANs can cross a trunk.
- Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
- Use show vlan brief to verify access VLANs.
- Use show interfaces trunk to verify trunk state and allowed VLANs.
- Do not treat every same-VLAN issue as a routing problem.
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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?
Access ports place end devices into a single VLAN.
What is the correct answer to this question?
The correct answer is: NAT is not configured or is misconfigured on the router — Since users can reach internal resources and the default gateway, the problem is likely at the router's NAT configuration. Outbound traffic typically requires NAT (Network Address Translation) to translate private IP addresses to a public IP address. If NAT is misconfigured or missing, packets will not be properly routed to the internet.
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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