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What is the main purpose of a VLAN on a switch?

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What is the main purpose of a VLAN on a switch?

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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

To create a separate Layer 2 broadcast domain

Correct. VLANs create separate broadcast domains.

B

Distractor review

To encrypt user traffic on the switch

VLANs do not inherently encrypt traffic.

C

Distractor review

To increase the physical speed of switch ports

VLANs do not change interface speed.

D

Distractor review

To replace the need for a default gateway

Devices still need a gateway to reach other subnets.

Common exam trap

Common exam trap: answer the scenario, not the keyword

A frequent exam trap is selecting answers that attribute VLAN functionality to encryption or speed improvements. VLANs do not encrypt user traffic; encryption is handled by other technologies like IPsec or MACsec. Similarly, VLANs do not increase the physical speed of switch ports; port speed is determined by hardware capabilities and configuration. Another common mistake is believing VLANs eliminate the need for a default gateway; however, devices in different VLANs still require a router or Layer 3 device to communicate. Misunderstanding these distinctions can lead to incorrect answers that confuse VLAN segmentation with unrelated network functions.

Technical deep dive

How to think about this question

A VLAN (Virtual Local Area Network) is a logical segmentation of a physical switch into multiple distinct broadcast domains at Layer 2. By assigning switch ports to different VLANs, network administrators can isolate traffic so that broadcasts from one VLAN do not propagate to others. This segmentation improves network efficiency and security by limiting broadcast traffic and controlling which devices can communicate directly at Layer 2. In Cisco switches, VLANs are configured by assigning ports to VLAN IDs, effectively grouping devices into separate Layer 2 domains. Each VLAN acts as its own broadcast domain, meaning that broadcast frames are confined within that VLAN. This separation is crucial for reducing unnecessary traffic and improving performance. Devices in different VLANs require routing (Layer 3) to communicate, typically through a router or a Layer 3 switch acting as a default gateway. A common exam trap is confusing VLANs with features like encryption or speed enhancements. VLANs do not encrypt traffic nor do they affect the physical speed of switch ports. Additionally, VLANs do not replace the need for a default gateway; inter-VLAN communication requires routing. Understanding that VLANs primarily create separate Layer 2 broadcast domains helps avoid these misconceptions and correctly answers questions about VLAN functionality in Cisco networking.

KKey Concepts to Remember

  • A VLAN logically segments a physical switch into multiple separate Layer 2 broadcast domains to isolate traffic.
  • Broadcast frames sent within a VLAN are confined to that VLAN and do not propagate to other VLANs on the same switch.
  • Devices assigned to different VLANs require a Layer 3 device, such as a router or Layer 3 switch, to communicate between VLANs.
  • VLANs improve network performance by reducing unnecessary broadcast traffic and enhancing traffic management.
  • VLAN configuration on Cisco switches involves assigning switch ports to specific VLAN IDs to control broadcast domains.
  • VLANs do not provide encryption or security features; encryption must be implemented with separate technologies.
  • The physical speed of switch ports is independent of VLAN configuration and is determined by hardware and port settings.
  • A default gateway is still required for devices in VLANs to communicate outside their local broadcast domain.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

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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 router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?

Question 2

A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?

Question 3

What is the OSPF metric called?

Question 4

A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?

Question 5

A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?

Question 6

A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?

FAQ

Questions learners often ask

What does this 200-301 question test?

A VLAN logically segments a physical switch into multiple separate Layer 2 broadcast domains to isolate traffic.

What is the correct answer to this question?

The correct answer is: To create a separate Layer 2 broadcast domain — A VLAN separates switch ports into distinct Layer 2 broadcast domains, improving segmentation and reducing unnecessary broadcast scope.

What should I do if I get this 200-301 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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