Implement a small routed network

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These questions are based on 642-822 – Interconnecting Cisco Networking Devices Part 1.


Objective: Implement a small routed network
Sub-Objective: Perform and verify routing configuration tasks for a static or default route given specific routing requirements


Single Answer, Multiple Choice


You have enabled the following commands on a router interface to enable interVLAN routing between hosts A and B on a switch:


routerA(config)# interface fastethernet 0/0
routerA(config-if)#no shut down
routerA(config)# interface fastethernet 0/0.1
routerA(config-subif)#encapsulation dot1q 20
routerA(config-if)#ip address
routerA(config)# interface fastethernet 0/0.2
routerA(config-if)#ip address


You have verified that the switch is configured correctly. The hosts on the switch can ping the default gateway. You can also ping the switch from the router. However, host A cannot communicate with host B.


What could be the possible problem?



  1. The command encapsulation dot1q is syntactically incorrect.
  2. 802.1q is not enabled on router subinterface 0.2.
  3. VLAN 1 needs to be created on the router.
  4. The no shutdown command is missing for subinterfaces.


B. 802.1q is not enabled on router subinterface 0.2.


In this scenario, the 802.1q protocol is not enabled on router subinterface 0.2. You must enable 802.1q on each subinterface that will participate in the interVLAN communication by using the encapsulation dot1q command.


You should not restate the encapsulation dot1q command. The encapsulation dot1q command is syntactically correct as presented. Switches, not routers, are used to create VLANs. Once the router main interface is enabled, all of its subinterfaces are enabled automatically.


VLAN1 does not need to be created on the router.


The no shutdown command is not missing for subinterfaces.


Cisco Documentation > Cisco 7600 Series Cisco IOS Software Configuration Guide, 12.2SX > Configuring IEEE 802.1Q Tunneling


Cisco > Support > Configuring Subinterfaces for IP InterVLAN Routing

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