A router has a single Ethernet connection to a switch. In the router configuration, the Ethernet interface has three sub-interfaces, each configured with ACLs applied to them and 802.1q trunks. Which

The correct answer is B. The switch has several VLANs configured on it.. The combination of sub-interfaces and 802.1q trunking is the classic 'router-on-a-stick' configuration used to route traffic between multiple VLANs over a single physical link. Each sub-interface on the router is assigned to a specific VLAN and carries 802.1q-tagged traffic for t

Security architecture

Question

A router has a single Ethernet connection to a switch. In the router configuration, the Ethernet interface has three sub-interfaces, each configured with ACLs applied to them and 802.1q trunks. Which of the following is MOST likely the reason for the sub-interfaces?

Options

AThe network uses the subnet of 255.255.255.128.
BThe switch has several VLANs configured on it.
CThe sub-interfaces are configured for VoIP traffic.
DThe sub-interfaces each implement quality of service.

How the community answered

(26 responses)

A
12% (3)
B
81% (21)
C
4% (1)
D
4% (1)

Explanation

The combination of sub-interfaces and 802.1q trunking is the classic 'router-on-a-stick' configuration used to route traffic between multiple VLANs over a single physical link. Each sub-interface on the router is assigned to a specific VLAN and carries 802.1q-tagged traffic for that VLAN. This is necessary when a switch has multiple VLANs configured and needs a single router interface to provide inter-VLAN routing. Option A (subnet mask) has no relationship to sub-interfaces or 802.1q. Option C (VoIP) and Option D (QoS) could be features configured on sub-interfaces, but they are not the reason sub-interfaces are created - the VLAN separation (Option B) is.

Topics

#VLAN#802.1q trunking#network segmentation#router sub-interfaces

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