Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
In a router-on-a-stick design, what is configured on the physical router interface connected to the switch?
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
One IP address for every VLAN on the physical interface itself only
Putting every VLAN address directly on the parent interface does not provide the required VLAN separation.
B
Distractor review
No subinterfaces; the switch handles all inter-VLAN routing internally
That describes multilayer switching, not router-on-a-stick.
C
Best answer
Subinterfaces with 802.1Q encapsulation for each routed VLAN
Correct. Subinterfaces with dot1q encapsulation are the key configuration element.
D
Distractor review
A serial encapsulation setting for each VLAN
Serial encapsulation is unrelated to VLAN trunking on Ethernet.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is selecting the option that assigns a single IP address directly to the physical router interface for all VLANs. This is incorrect because it fails to maintain VLAN separation and prevents proper inter-VLAN routing. Another tempting mistake is to assume the switch handles inter-VLAN routing internally without router subinterfaces, which actually describes multilayer switching, not router-on-a-stick. Candidates must remember that router-on-a-stick requires subinterfaces with 802.1Q encapsulation to route traffic between VLANs over a single physical link.
Technical deep dive
How to think about this question
Router-on-a-stick is a network design where a single physical router interface is used to route traffic between multiple VLANs on a switch. This is achieved by creating multiple logical subinterfaces on the router's physical interface, each representing a different VLAN. Each subinterface is configured with an IP address and uses 802.1Q encapsulation to tag traffic with the appropriate VLAN ID, enabling the router to distinguish and route traffic between VLANs correctly. The key configuration rule in router-on-a-stick is that the physical interface itself does not have an IP address assigned directly. Instead, each subinterface is assigned an IP address corresponding to its VLAN. The router uses 802.1Q encapsulation on each subinterface to identify VLAN tags on incoming frames. This encapsulation allows the router to process traffic for multiple VLANs over a single physical link, which is typically connected to a trunk port on the switch. A common exam trap is to incorrectly assign one IP address directly on the physical interface for all VLANs, which breaks VLAN separation and routing functionality. Another confusion is to assume that the switch handles inter-VLAN routing internally without subinterfaces, which describes multilayer switching, not router-on-a-stick. Practically, router-on-a-stick is useful in smaller networks or lab environments where a single router interface must handle multiple VLANs, but it can become a bottleneck in larger networks due to bandwidth limitations on the single physical link.
KKey Concepts to Remember
- Router-on-a-stick uses a single physical router interface divided into multiple logical subinterfaces to route between VLANs.
- Each subinterface on the router is configured with an IP address specific to its VLAN to enable inter-VLAN routing.
- 802.1Q encapsulation is applied on each subinterface to tag traffic with the VLAN ID for proper VLAN identification.
- The physical router interface itself does not have an IP address assigned when using router-on-a-stick.
- Switch ports connected to the router interface must be configured as trunk ports to carry multiple VLANs.
- Router-on-a-stick design is distinct from multilayer switching, which performs inter-VLAN routing within the switch.
- Assigning one IP address directly on the physical interface for all VLANs breaks VLAN separation and routing.
- Router-on-a-stick can create a bandwidth bottleneck since all VLAN traffic shares a single physical interface.
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?
Router-on-a-stick uses a single physical router interface divided into multiple logical subinterfaces to route between VLANs.
What is the correct answer to this question?
The correct answer is: Subinterfaces with 802.1Q encapsulation for each routed VLAN — Router-on-a-stick uses one physical router interface with multiple logical subinterfaces. Each subinterface is associated with a VLAN using 802.1Q encapsulation and gets an IP address for that VLAN.
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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